Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail)

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Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($)
$ in Thousands
Mar. 31, 2016
Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale $ 675,032 $ 698,296
Municipal bonds-tax exempt [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 166,126 163,902
Municipal bonds-taxable [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 14,313 14,033
Collateralized mortgage obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 92,129 96,986
U.S. government agency securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 40,040 47,822
Recurring Basis [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 675,032 698,296
Recurring Basis [Member] | SBA loan pools securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 60,607 63,266
Recurring Basis [Member] | Municipal bonds-tax exempt [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 166,126 163,902
Recurring Basis [Member] | Municipal bonds-taxable [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 14,313 14,033
Recurring Basis [Member] | Collateralized mortgage obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 92,129 96,986
Recurring Basis [Member] | Mortgage-backed securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 273,590 284,381
Recurring Basis [Member] | U.S. government agency securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 40,040 47,822
Recurring Basis [Member] | Corporate bonds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 4,998 4,993
Recurring Basis [Member] | U.S treasury securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 160 160
Recurring Basis [Member] | Mutual funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 23,069 22,753
Recurring Basis [Member] | Fair Value, Inputs, Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 23,229 22,913
Recurring Basis [Member] | Fair Value, Inputs, Level 1 [Member] | SBA loan pools securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 1 [Member] | Municipal bonds-tax exempt [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 1 [Member] | Municipal bonds-taxable [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 1 [Member] | Collateralized mortgage obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 1 [Member] | Mortgage-backed securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. government agency securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate bonds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 1 [Member] | U.S treasury securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 160 160
Recurring Basis [Member] | Fair Value, Inputs, Level 1 [Member] | Mutual funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 23,069 22,753
Recurring Basis [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 651,803 675,383
Recurring Basis [Member] | Fair Value, Inputs, Level 2 [Member] | SBA loan pools securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 60,607 63,266
Recurring Basis [Member] | Fair Value, Inputs, Level 2 [Member] | Municipal bonds-tax exempt [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 166,126 163,902
Recurring Basis [Member] | Fair Value, Inputs, Level 2 [Member] | Municipal bonds-taxable [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 14,313 14,033
Recurring Basis [Member] | Fair Value, Inputs, Level 2 [Member] | Collateralized mortgage obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 92,129 96,986
Recurring Basis [Member] | Fair Value, Inputs, Level 2 [Member] | Mortgage-backed securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 273,590 284,381
Recurring Basis [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. government agency securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 40,040 47,822
Recurring Basis [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate bonds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 4,998 4,993
Recurring Basis [Member] | Fair Value, Inputs, Level 2 [Member] | U.S treasury securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 2 [Member] | Mutual funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 3 [Member] | SBA loan pools securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 3 [Member] | Municipal bonds-tax exempt [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 3 [Member] | Municipal bonds-taxable [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 3 [Member] | Collateralized mortgage obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 3 [Member] | Mortgage-backed securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. government agency securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate bonds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 3 [Member] | U.S treasury securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale 0 0
Recurring Basis [Member] | Fair Value, Inputs, Level 3 [Member] | Mutual funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total securities available for sale $ 0 $ 0