Securities - Estimated Fair Value and Unrealized Loss of Securities Available-for-Sale and Held-to-Maturity (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Total securities, Less than 12 months, Estimated Fair Value	$ 176,316
Total securities, Less than 12 months, Unrealized Losses	(3,998)
Total securities, 12 months or longer, Estimated Fair Value	69,583
Total securities, 12 months or longer, Unrealized Losses	(7,974)
Total securities, Estimated Fair Value	245,899
Total securities, Unrealized Losses	(11,972)
Investment Securities [Member] | Equity Investments [Member]
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Available-for-sale, Less than 12 months, Estimated Market Value	1,032
Available-for-sale, Less than 12 months, Unrealized Losses	(21)
Available-for-sale, 12 months or longer, Estimated Market Value	0
Available-for-sale, 12 months or longer, Unrealized Losses	0
Available-for-sale, Total, Estimated Market Value	1,032
Available-for-sale, Total, Unrealized Losses	(21)
Held-to-Maturity Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Held-to-maturity, Less than 12 months, Estimated Fair Value	175,284	246,105
Held-to-maturity, Less than 12 months, Unrealized Losses	(3,977)	(8,334)
Held-to-maturity, 12 months or longer, Estimated Fair Value	69,583	45,403
Held-to-maturity, 12 months or longer, Unrealized Losses	(7,974)	(10,754)
Held-to-maturity, Total, Estimated Fair Value	244,867	291,508
Held-to-maturity, Total, Unrealized Losses	(11,951)	(19,088)
Held-to-Maturity Securities [Member] | Investment Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Held-to-maturity, Less than 12 months, Estimated Fair Value	1,037	39,273
Held-to-maturity, Less than 12 months, Unrealized Losses	(1)	(175)
Held-to-maturity, 12 months or longer, Estimated Fair Value	69,583	45,403
Held-to-maturity, 12 months or longer, Unrealized Losses	(7,974)	(10,754)
Held-to-maturity, Total, Estimated Fair Value	70,620	84,676
Held-to-maturity, Total, Unrealized Losses	(7,975)	(10,929)
Held-to-Maturity Securities [Member] | Investment Securities [Member] | U.S. Agency Obligations [Member]
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Held-to-maturity, Less than 12 months, Estimated Fair Value	0	35,747
Held-to-maturity, Less than 12 months, Unrealized Losses	0	(144)
Held-to-maturity, 12 months or longer, Estimated Fair Value	20,446	0
Held-to-maturity, 12 months or longer, Unrealized Losses	(57)	0
Held-to-maturity, Total, Estimated Fair Value	20,446	35,747
Held-to-maturity, Total, Unrealized Losses	(57)	(144)
Held-to-Maturity Securities [Member] | Investment Securities [Member] | State And Municipal Obligation [Member]
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Held-to-maturity, Less than 12 months, Estimated Fair Value	1,037	3,526
Held-to-maturity, Less than 12 months, Unrealized Losses	(1)	(31)
Held-to-maturity, 12 months or longer, Estimated Fair Value	2,047	1,153
Held-to-maturity, 12 months or longer, Unrealized Losses	(7)	(4)
Held-to-maturity, Total, Estimated Fair Value	3,084	4,679
Held-to-maturity, Total, Unrealized Losses	(8)	(35)
Held-to-Maturity Securities [Member] | Investment Securities [Member] | Corporate Debt Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Held-to-maturity, Less than 12 months, Estimated Fair Value	0	0
Held-to-maturity, Less than 12 months, Unrealized Losses	0	0
Held-to-maturity, 12 months or longer, Estimated Fair Value	47,090	44,250
Held-to-maturity, 12 months or longer, Unrealized Losses	(7,910)	(10,750)
Held-to-maturity, Total, Estimated Fair Value	47,090	44,250
Held-to-maturity, Total, Unrealized Losses	(7,910)	(10,750)
Held-to-Maturity Securities [Member] | Mortgage-Backed Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Held-to-maturity, Less than 12 months, Estimated Fair Value	174,247	206,832
Held-to-maturity, Less than 12 months, Unrealized Losses	(3,976)	(8,159)
Held-to-maturity, 12 months or longer, Estimated Fair Value	0	0
Held-to-maturity, 12 months or longer, Unrealized Losses	0	0
Held-to-maturity, Total, Estimated Fair Value	174,247	206,832
Held-to-maturity, Total, Unrealized Losses	(3,976)	(8,159)
Held-to-Maturity Securities [Member] | Mortgage-Backed Securities [Member] | FHLMC [Member]
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Held-to-maturity, Less than 12 months, Estimated Fair Value	104,591	122,365
Held-to-maturity, Less than 12 months, Unrealized Losses	(2,218)	(4,552)
Held-to-maturity, 12 months or longer, Estimated Fair Value	0	0
Held-to-maturity, 12 months or longer, Unrealized Losses	0	0
Held-to-maturity, Total, Estimated Fair Value	104,591	122,365
Held-to-maturity, Total, Unrealized Losses	(2,218)	(4,552)
Held-to-Maturity Securities [Member] | Mortgage-Backed Securities [Member] | FNMA [Member]
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Held-to-maturity, Less than 12 months, Estimated Fair Value	69,656	84,467
Held-to-maturity, Less than 12 months, Unrealized Losses	(1,758)	(3,607)
Held-to-maturity, 12 months or longer, Estimated Fair Value	0	0
Held-to-maturity, 12 months or longer, Unrealized Losses	0	0
Held-to-maturity, Total, Estimated Fair Value	69,656	84,467
Held-to-maturity, Total, Unrealized Losses	$ (1,758)	$ (3,607)