Investment Securities - Contractual Maturities of Investment Securities Available for Sale (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014
Schedule of Available-for-sale Securities [Line Items]
Due in one year, Amortized Cost	$ 115
Due after one year through five years, Amortized Cost	74,141
Due after five years through ten years, Amortized Cost	85,769
Due after ten years, Amortized Cost	130,668
Total investment securities available for sale, Amortized Cost	795,545
Due in one year, Fair Value	115
Due after one year through five years, Fair Value	75,773
Due after five years through ten years, Fair Value	82,334
Due after ten years, Fair Value	122,907
Total investment securities available for sale, Fair Value	783,205
Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities without a single maturity date, Amortized Cost	481,781
Securities without a single maturity date, Fair Value	478,132
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities without a single maturity date, Amortized Cost	23,071
Securities without a single maturity date, Fair Value	$ 23,944