Quarterly report pursuant to Section 13 or 15(d)

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

v3.10.0.1
Securities - Summary of Investment Securities Available for Sale (Detail) - USD ($)
$ in Thousands
Jun. 30, 2018
Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost $ 578,621 $ 581,992
Gross Unrealized Gain 82 2,096
Gross Unrealized Loss 13,174 5,284
Estimated Fair Value 565,529 578,804
Mortgage-backed securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 331,126 306,166
Gross Unrealized Gain 1 145
Gross Unrealized Loss 8,276 2,702
Collateralized mortgage obligations [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 124,761 119,658
Gross Unrealized Gain 7 8
Gross Unrealized Loss 3,379 1,898
U.S. government agency securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 7,499 7,499
Gross Unrealized Gain 0 0
Gross Unrealized Loss 139 85
Municipal bonds-tax exempt [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 115,235 125,601
Gross Unrealized Gain 74 1,943
Gross Unrealized Loss $ 1,380 69
U.S treasury securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost   152
Gross Unrealized Gain   0
Gross Unrealized Loss   0
Mutual funds [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost   22,916
Gross Unrealized Gain   0
Gross Unrealized Loss   $ 530