Investment Securities Held to Maturity - Securities Held to Maturity by Contractual Maturity (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Held-to-maturity Securities [Line Items]
Due in one year or less, Amortized cost	$ 25,201
Due after one year through five years, Amortized cost	48,999
Due after five years through ten years, Amortized cost	118,609
Due after ten years, Amortized cost	159,418
Amortized cost	357,500	359,464
Due in one year or less, Fair value	25,331
Due after one year through five years, Fair value	50,098
Due after five years through ten years, Fair value	120,390
Due after ten years, Fair value	154,574
Fair value	355,913	374,916
Mortgage-Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	5,273	11,123
Fair value	$ 5,520	$ 11,583