Investment Securities - Summary of Amortized Cost and Market Values of Investment Securities with Gross Unrealized Gains and Losses (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 294,259	$ 403,005
Gross Unrealized Gains	1,063	2,997
Gross Unrealized Losses Less Than One Year	(15,651)	(647)
Gross Unrealized Losses Greater Than One Year	(1,952)
Estimated Market Value	277,719	405,355
Amortized Cost	94,904
Gross Unrealized Gains	106
Gross Unrealized Losses Less Than One Year	(4,044)
Gross Unrealized Losses Greater Than One Year
Estimated Market Value	94,904
Municipal securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	23,240	61,907
Gross Unrealized Gains	140	884
Gross Unrealized Losses Less Than One Year	(213)	(44)
Estimated Market Value	23,167	62,747
Amortized Cost	44,294
Gross Unrealized Gains	94
Gross Unrealized Losses Less Than One Year	(398)
Gross Unrealized Losses Greater Than One Year
Estimated Market Value	43,990
Mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	57,010	152,481
Gross Unrealized Gains	447	1,615
Gross Unrealized Losses Less Than One Year	(1,897)	(254)
Gross Unrealized Losses Greater Than One Year	(16)
Estimated Market Value	55,544	153,842
Amortized Cost	50,610
Gross Unrealized Gains	12
Gross Unrealized Losses Less Than One Year	(3,646)
Gross Unrealized Losses Greater Than One Year
Estimated Market Value	46,976
U.S. government agency securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	163,964	128,665
Gross Unrealized Gains	81	83
Gross Unrealized Losses Less Than One Year	(10,991)	(1)
Gross Unrealized Losses Greater Than One Year	(1,731)
Estimated Market Value	151,323	128,747
U.S. Treasury securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	13,022	10,040
Gross Unrealized Gains		5
Gross Unrealized Losses Less Than One Year	(873)
Estimated Market Value	12,149	10,045
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	37,023	49,912
Gross Unrealized Gains	395	410
Gross Unrealized Losses Less Than One Year	(1,677)	(348)
Gross Unrealized Losses Greater Than One Year	(205)
Estimated Market Value	$ 35,536	$ 49,974