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
Sep. 30, 2017
Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost $ 597,944 $ 521,053
Gross Unrealized Gain 3,233 1,164
Gross Unrealized Loss 2,737 5,253
Estimated Fair Value 598,440 516,964
Municipal bonds-tax exempt [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 146,177 159,789
Gross Unrealized Gain 2,424 236
Gross Unrealized Loss 77 1,995
Municipal bonds-taxable [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost   13,391
Gross Unrealized Gain   319
Gross Unrealized Loss   9
Corporate bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost   5,010
Gross Unrealized Gain   5
Gross Unrealized Loss   0
Mutual funds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 22,916 22,916
Gross Unrealized Gain 0 0
Gross Unrealized Loss 380 522
Mortgage-backed securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 310,111 230,489
Gross Unrealized Gain 793 598
Gross Unrealized Loss 1,154 1,457
Collateralized mortgage obligations [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 107,052 77,447
Gross Unrealized Gain 16 6
Gross Unrealized Loss 944 1,002
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 42 58
SBA loan pool securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 4,036 4,356
Gross Unrealized Gain 0 0
Gross Unrealized Loss 140 210
U.S. treasury securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 153 156
Gross Unrealized Gain 0 0
Gross Unrealized Loss 0 0
Collateralized home equity conversion mortgages [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Estimated Fair Value $ 8,100 $ 52,900