Securities - Schedule of Unrealized Loss and Fair Value on Investments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Total temporarily impaired securities, Less than 12 months, Fair Value	$ 430,645	$ 234,315
Total temporarily impaired securities, Less than 12 months, Unrealized Losses	(15,561)	(1,811)
Total temporarily impaired securities,12 months or longer, Fair Value	80,825	13,939
Total temporarily impaired securities, 12 months or longer, Unrealized Losses	(4,442)	(185)
Total temporarily impaired securities, Fair Value	511,470	248,254
Total temporarily impaired securities, Unrealized Losses	(20,003)	(1,996)
Mortgage-Backed Securities of U.S. Government Sponsored Entities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	33,425	54,289
Less than 12 months, Unrealized Losses	(2,045)	(469)
12 months or longer, Fair Value	35,043	0
12 months or longer, Unrealized Losses	(2,144)	0
Fair Value, Total	68,468	54,289
Unrealized Losses, Total	(4,189)	(469)
Collateralized Mortgage Obligations of U.S. Government Sponsored Entities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	287,312	150,057
Less than 12 months, Unrealized Losses	(12,450)	(901)
12 months or longer, Fair Value	45,657	4,593
12 months or longer, Unrealized Losses	(2,297)	(93)
Fair Value, Total	332,969	154,650
Unrealized Losses, Total	(14,747)	(994)
Private Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	29,574
Less than 12 months, Unrealized Losses	(226)
12 months or longer, Fair Value	0
12 months or longer, Unrealized Losses	0
Fair Value, Total	29,574
Unrealized Losses, Total	(226)
Private Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	47,653	29,969
Less than 12 months, Unrealized Losses	(413)	(441)
12 months or longer, Fair Value	0	9,221
12 months or longer, Unrealized Losses	0	(89)
Fair Value, Total	47,653	39,190
Unrealized Losses, Total	(413)	(530)
Collateralized Loan Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	32,179
Less than 12 months, Unrealized Losses	(413)
12 months or longer, Fair Value	0
12 months or longer, Unrealized Losses	0
Fair Value, Total	32,179
Unrealized Losses, Total	(413)
Obligations of State and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	502	0
Less than 12 months, Unrealized Losses	(14)	0
12 months or longer, Fair Value	125	125
12 months or longer, Unrealized Losses	(1)	(3)
Fair Value, Total	627	125
Unrealized Losses, Total	$ (15)	$ (3)