Contractual Maturity Information for Securities Held to Maturity (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Investments Debt And Equity Securities [Abstract]
Due in 1 year or less, Amortized Cost	$ 61
Due after 1 year through 5 years, Amortized Cost	28,051
Due after 5 years through 10 years, Amortized Cost	97,997
Due after 10 years, Amortized Cost	112,690
Total securities held to maturity, Amortized Cost	238,799	209,770
Due in 1 year or less, Fair Value	69
Due after 1 year through 5 years, Fair Value	31,680
Due after 5 years through 10 years, Fair Value	110,674
Due after 10 years, Fair Value	127,268
Held to Maturity, Fair value	$ 269,691	$ 231,510