Quarterly report pursuant to Section 13 or 15(d)

Securities - Summary of Investment Securities Available for Sale (Detail)

v3.8.0.1
Securities - Summary of Investment Securities Available for Sale (Detail) - USD ($)
$ in Thousands
Mar. 31, 2018
Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost $ 581,874 $ 581,992
Gross Unrealized Gain 233 2,096
Gross Unrealized Loss 11,756 5,284
Estimated Fair Value 570,351 578,804
Mortgage-backed securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 322,186  
Gross Unrealized Gain 6  
Gross Unrealized Loss 7,223  
Estimated Fair Value 314,969  
Collateralized mortgage obligations [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 127,125  
Gross Unrealized Gain 8  
Gross Unrealized Loss 2,945  
Estimated Fair Value 124,188  
Mortgage-backed securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost   306,166
Gross Unrealized Gain   145
Gross Unrealized Loss   2,702
Estimated Fair Value   303,609
U.S. government agency securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 7,499 7,499
Gross Unrealized Gain 0 0
Gross Unrealized Loss 131 85
Estimated Fair Value 7,368 7,414
Municipal bonds-tax exempt [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 125,064 125,601
Gross Unrealized Gain 219 1,943
Gross Unrealized Loss 1,457 69
Estimated Fair Value $ 123,826 127,475
U.S treasury securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost   152
Gross Unrealized Gain   0
Gross Unrealized Loss   0
Estimated Fair Value   152
Mutual funds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost   22,916
Gross Unrealized Gain   0
Gross Unrealized Loss   530
Estimated Fair Value   22,386
Collateralized mortgage obligations [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost   119,658
Gross Unrealized Gain   8
Gross Unrealized Loss   1,898
Estimated Fair Value   $ 117,768