Investment Securities - Contractual Maturities of Investments Securities Available for Sale (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Due in one year, Amortized Cost	$ 160
Due after one year through five years, Amortized Cost	55,700
Due after five years through ten years, Amortized Cost	106,009
Due after ten years, Amortized Cost	132,637
Total investment securities available for sale, Amortized Cost	866,904
Due in one year, Fair Value	161
Due after one year through five years, Fair Value	54,804
Due after five years through ten years, Fair Value	101,992
Due after ten years, Fair Value	116,648
Total investment securities available for sale, Fair Value	829,692
Residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities without a single maturity date, Amortized Cost	524,781
Securities without a single maturity date, Fair Value	508,029
Equity securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities without a single maturity date, Amortized Cost	47,617
Securities without a single maturity date, Fair Value	$ 48,058