Annual report pursuant to Section 13 and 15(d)

Loans and Leases - Analysis of Gross Loans and Leases, Disaggregated by Class (Detail)

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Loans and Leases - Analysis of Gross Loans and Leases, Disaggregated by Class (Detail) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total loans and Leases $ 4,304,458 $ 3,844,769
Accruing 90 Days or More Past Due 0 0
Real estate loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total loans and Leases 3,590,914 3,278,375
Real estate loans [Member] | Hotel/motel [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total loans and Leases 681,325 651,158
Real estate loans [Member] | Construction [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total loans and Leases 55,190 55,962
Real estate loans [Member] | Residential property [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total loans and Leases 521,853 338,767
Commercial and industrial loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total loans and Leases 399,201 300,220
Commercial and industrial loans [Member] | Commercial term [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total loans and Leases 182,685 138,168
Commercial and industrial loans [Member] | Commercial lines of credit [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total loans and Leases 181,894 136,231
Commercial and industrial loans [Member] | International loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total loans and Leases 34,622 25,821
Leases Receivable [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total loans and Leases 297,284 243,294
Consumer loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total loans and Leases 17,059 22,880
30-59 Days Past Due [Member] | Commercial and industrial loans [Member] | International loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 0  
30-59 Days Past Due [Member] | Leases Receivable [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 2,295 2,090
Non-PCI Loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 16,826 10,346
Current 4,279,884 3,824,560
Total loans and Leases 4,296,710 3,834,906
Accruing 90 Days or More Past Due 0 0
Non-PCI Loans [Member] | Real estate loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 7,780 5,941
Current 3,575,475 3,262,757
Total loans and Leases 3,583,255 3,268,698
Accruing 90 Days or More Past Due 0 0
Non-PCI Loans [Member] | Real estate loans [Member] | Retail [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 307 380
Current 913,321 857,249
Total loans and Leases 913,628 857,629
Accruing 90 Days or More Past Due 0 0
Non-PCI Loans [Member] | Real estate loans [Member] | Hotel/motel [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 3,819 1,683
Current 675,864 647,857
Total loans and Leases 679,683 649,540
Accruing 90 Days or More Past Due 0 0
Non-PCI Loans [Member] | Real estate loans [Member] | Other [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 3,045 2,636
Current 1,410,807 1,365,140
Total loans and Leases 1,413,852 1,367,776
Accruing 90 Days or More Past Due 0 0
Non-PCI Loans [Member] | Real estate loans [Member] | Construction [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 0 0
Current 55,190 55,962
Total loans and Leases 55,190 55,962
Accruing 90 Days or More Past Due 0 0
Non-PCI Loans [Member] | Real estate loans [Member] | Residential property [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 609 1,242
Current 520,293 336,549
Total loans and Leases 520,902 337,791
Accruing 90 Days or More Past Due 0 0
Non-PCI Loans [Member] | Commercial and industrial loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total loans and Leases 399,152 300,084
Non-PCI Loans [Member] | Commercial and industrial loans [Member] | Commercial term [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 1,821 637
Current 180,815 137,395
Total loans and Leases 182,636 138,032
Accruing 90 Days or More Past Due 0 0
Non-PCI Loans [Member] | Commercial and industrial loans [Member] | Commercial lines of credit [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 432 0
Current 181,462 136,231
Total loans and Leases 181,894 136,231
Accruing 90 Days or More Past Due 0 0
Non-PCI Loans [Member] | Commercial and industrial loans [Member] | International loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 0 80
Current 34,622 25,741
Total loans and Leases 34,622 25,821
Accruing 90 Days or More Past Due 0 0
Non-PCI Loans [Member] | Leases Receivable [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 6,793 3,518
Current 290,491 239,776
Total loans and Leases 297,284 243,294
Non-PCI Loans [Member] | Consumer loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 0 170
Current 17,019 22,660
Total loans and Leases 17,019 22,830
Accruing 90 Days or More Past Due 0 0
Non-PCI Loans [Member] | 30-59 Days Past Due [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 8,341 5,277
Non-PCI Loans [Member] | 30-59 Days Past Due [Member] | Real estate loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 5,371 2,453
Non-PCI Loans [Member] | 30-59 Days Past Due [Member] | Real estate loans [Member] | Retail [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 96 9
Non-PCI Loans [Member] | 30-59 Days Past Due [Member] | Real estate loans [Member] | Hotel/motel [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 3,421 1,037
Non-PCI Loans [Member] | 30-59 Days Past Due [Member] | Real estate loans [Member] | Other [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 1,245 677
Non-PCI Loans [Member] | 30-59 Days Past Due [Member] | Real estate loans [Member] | Construction [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 0 0
Non-PCI Loans [Member] | 30-59 Days Past Due [Member] | Real estate loans [Member] | Residential property [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 609 730
Non-PCI Loans [Member] | 30-59 Days Past Due [Member] | Commercial and industrial loans [Member] | Commercial term [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 425 484
Non-PCI Loans [Member] | 30-59 Days Past Due [Member] | Commercial and industrial loans [Member] | Commercial lines of credit [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 250 0
Non-PCI Loans [Member] | 30-59 Days Past Due [Member] | Commercial and industrial loans [Member] | International loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable   80
Non-PCI Loans [Member] | 30-59 Days Past Due [Member] | Consumer loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 0 170
Non-PCI Loans [Member] | 60-89 Days Past Due [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 2,859 2,079
Non-PCI Loans [Member] | 60-89 Days Past Due [Member] | Real estate loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 1,348 994
Non-PCI Loans [Member] | 60-89 Days Past Due [Member] | Real estate loans [Member] | Retail [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 15 137
Non-PCI Loans [Member] | 60-89 Days Past Due [Member] | Real estate loans [Member] | Hotel/motel [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 0 46
Non-PCI Loans [Member] | 60-89 Days Past Due [Member] | Real estate loans [Member] | Other [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 1,333 722
Non-PCI Loans [Member] | 60-89 Days Past Due [Member] | Real estate loans [Member] | Construction [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 0 0
Non-PCI Loans [Member] | 60-89 Days Past Due [Member] | Real estate loans [Member] | Residential property [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 0 89
Non-PCI Loans [Member] | 60-89 Days Past Due [Member] | Commercial and industrial loans [Member] | Commercial term [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 567 42
Non-PCI Loans [Member] | 60-89 Days Past Due [Member] | Commercial and industrial loans [Member] | Commercial lines of credit [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 0 0
Non-PCI Loans [Member] | 60-89 Days Past Due [Member] | Commercial and industrial loans [Member] | International loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 0 0
Non-PCI Loans [Member] | 60-89 Days Past Due [Member] | Leases Receivable [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 944 1,043
Non-PCI Loans [Member] | 60-89 Days Past Due [Member] | Consumer loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 0 0
Non-PCI Loans [Member] | 90 Days or More Past Due [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 5,626 2,990
Non-PCI Loans [Member] | 90 Days or More Past Due [Member] | Real estate loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 1,061 2,494
Non-PCI Loans [Member] | 90 Days or More Past Due [Member] | Real estate loans [Member] | Retail [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 196 234
Non-PCI Loans [Member] | 90 Days or More Past Due [Member] | Real estate loans [Member] | Hotel/motel [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 398 600
Non-PCI Loans [Member] | 90 Days or More Past Due [Member] | Real estate loans [Member] | Other [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 467 1,237
Non-PCI Loans [Member] | 90 Days or More Past Due [Member] | Real estate loans [Member] | Construction [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 0 0
Non-PCI Loans [Member] | 90 Days or More Past Due [Member] | Real estate loans [Member] | Residential property [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 0 423
Non-PCI Loans [Member] | 90 Days or More Past Due [Member] | Commercial and industrial loans [Member] | Commercial term [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 829 111
Non-PCI Loans [Member] | 90 Days or More Past Due [Member] | Commercial and industrial loans [Member] | Commercial lines of credit [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 182 0
Non-PCI Loans [Member] | 90 Days or More Past Due [Member] | Commercial and industrial loans [Member] | International loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 0 0
Non-PCI Loans [Member] | 90 Days or More Past Due [Member] | Leases Receivable [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable 3,554 385
Non-PCI Loans [Member] | 90 Days or More Past Due [Member] | Consumer loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Past due loans and leases receivable $ 0 $ 0