Quarterly report pursuant to Section 13 or 15(d)

Securities - Schedule of Amortized Cost and Estimated Fair Value of Investment Securities by Contractual Maturity (Detail)

v3.3.0.814
Securities - Schedule of Amortized Cost and Estimated Fair Value of Investment Securities by Contractual Maturity (Detail) - USD ($)
$ in Thousands
Sep. 30, 2015
Dec. 31, 2014
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within one year, Amortized Cost $ 11,999  
Available-for-Sale Over one year through five years, Amortized Cost 14,316  
Available-for-Sale Over five years through ten years, Amortized Cost 106,586  
Available-for-Sale Over ten years, Amortized Cost 72,395  
Available-for-Sale, Amortized Cost 667,403 $ 1,061,703
Available-for-Sale Within one year, Estimated Fair Value 11,994  
Available-for-Sale Over one year through five years, Estimated Fair Value 14,342  
Available-for-Sale Over five years through ten years, Estimated Fair Value 106,963  
Available-for-Sale Over ten years, Estimated Fair Value 72,216  
Securities available for sale 669,340 1,060,717
Collateralized mortgage obligations [Member]    
Summary of Investment Holdings [Line Items]    
Available-for-Sale, Amortized Cost 116,145 188,704
Securities available for sale 116,314 188,047
Mortgage-backed securities [Member]    
Summary of Investment Holdings [Line Items]    
Available-for-Sale, Amortized Cost 323,046 571,678
Securities available for sale 324,504 573,286
Other securities [Member]    
Summary of Investment Holdings [Line Items]    
Available-for-Sale, Amortized Cost 22,916 22,916
Securities available for sale $ 23,007 $ 22,893