Securities - Amortized Cost and Fair Value of Debt Securities Available for Sale Securities by Contractual Maturity (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-Sale Securities [Line Items]
Due in one year or less, Amortized Cost	$ 2,726
Due from one year to five years, Amortized Cost	38,378
Due from five to ten years, Amortized Cost	69,252
Due after ten years, Amortized Cost	29,041
Mortgage-backed securities, Amortized cost	10,311
Mortgage-backed securities, Amortized Cost	488,838	336,710
Due in one year or less, Estimated Fair Value	2,740
Due from one year to five years, Estimated Fair Value	39,593
Due from five to ten years, Estimated Fair Value	67,888
Due after ten years, Estimated Fair Value	28,264
Mortgage-backed securities, Estimated Fair Value	347,750
Estimated Fair Value	486,235	346,909
Mortgage-Backed Securities [Member]
Schedule of Available-for-Sale Securities [Line Items]
Mortgage-backed securities, Amortized cost	349,441
Mortgage-backed securities, Amortized Cost	349,441	209,824
Estimated Fair Value	$ 347,750	$ 215,321