Securities - Summaries of Fair Values and Unrealized Losses of Securities, Segregated by Length of Impairment (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013 Security	Dec. 31, 2012 Security	Dec. 31, 2011
Schedule Of Securities [Line Items]
Number of available for sale securities, Less than 1 year	54	14
Number of available for sale securities, Greater than 1 year	14	13
Number of available for sale securities	68	27
Securities Available For Sale, Less than 12 Months, Fair Value	$ 734,257	$ 101,404
Securities Available For Sale, Less than 12 Months, Unrealized Losses	(26,101)	(1,275)
Securities Available For Sale, 12 Months or More, Fair Value	48,144	11,431
Securities Available For Sale, 12 Months or More, Unrealized Losses	(13,194)	(13,339)
Securities Available For Sale, Fair Value, Total	782,401	112,835
Securities Available For Sale, Unrealized Losses, Total	(39,295)	(14,614)
Number of held to maturity securities	80	3
Securities Held To Maturity, Less than 12 Months, Fair Value	669,220	16,325
Securities Held To Maturity, Less than 12 Months, Unrealized Losses	(24,379)	(100)
Securities Held To Maturity, Greater than 12 Months, Fair Value	15,674	477
Securities Held To Maturity, Greater than 12 Months, Unrealized Losses	(711)	(35)
Securities Held To Maturity, Fair Value, Total	684,894	16,802
Securities Held To Maturity, Unrealized Losses, Total	(25,090)	(135)	(1,879)
Less than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	78	2
Greater than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	2	1
U.S. Government-Sponsored Entities [Member]
Schedule Of Securities [Line Items]
Number of available for sale securities, Less than 1 year	17	3
Number of available for sale securities, Greater than 1 year
Number of available for sale securities	17	3
Securities Available For Sale, Less than 12 Months, Fair Value	232,962	44,868
Securities Available For Sale, Less than 12 Months, Unrealized Losses	(5,904)	(129)
Securities Available For Sale, 12 Months or More, Fair Value
Securities Available For Sale, 12 Months or More, Unrealized Losses
Securities Available For Sale, Fair Value, Total	232,962	44,868
Securities Available For Sale, Unrealized Losses, Total	(5,904)	(129)
Number of held to maturity securities	3	1
Securities Held To Maturity, Less than 12 Months, Fair Value	24,513	14,901
Securities Held To Maturity, Less than 12 Months, Unrealized Losses	(530)	(99)
Securities Held To Maturity, Greater than 12 Months, Fair Value	14,378
Securities Held To Maturity, Greater than 12 Months, Unrealized Losses	(621)
Securities Held To Maturity, Fair Value, Total	38,891	14,901
Securities Held To Maturity, Unrealized Losses, Total	(1,151)	(99)
U.S. Government-Sponsored Entities [Member] | Less than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	2	1
U.S. Government-Sponsored Entities [Member] | Greater than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	1
Agency Mortgage-Backed Securities [Member]
Schedule Of Securities [Line Items]
Number of available for sale securities, Less than 1 year	9
Number of available for sale securities, Greater than 1 year
Number of available for sale securities	9
Securities Available For Sale, Less than 12 Months, Fair Value	108,284
Securities Available For Sale, Less than 12 Months, Unrealized Losses	(1,303)
Securities Available For Sale, 12 Months or More, Fair Value
Securities Available For Sale, 12 Months or More, Unrealized Losses
Securities Available For Sale, Fair Value, Total	108,284
Securities Available For Sale, Unrealized Losses, Total	(1,303)
Number of held to maturity securities	25	1
Securities Held To Maturity, Less than 12 Months, Fair Value	308,864	1,424
Securities Held To Maturity, Less than 12 Months, Unrealized Losses	(5,942)	(1)
Securities Held To Maturity, Greater than 12 Months, Fair Value	1,296
Securities Held To Maturity, Greater than 12 Months, Unrealized Losses	(90)
Securities Held To Maturity, Fair Value, Total	310,160	1,424
Securities Held To Maturity, Unrealized Losses, Total	(6,032)	(1)
Agency Mortgage-Backed Securities [Member] | Less than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	24	1
Agency Mortgage-Backed Securities [Member] | Greater than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	1
Agency Collateralized Mortgage Obligations [Member]
Schedule Of Securities [Line Items]
Number of available for sale securities, Less than 1 year	26	3
Number of available for sale securities, Greater than 1 year	2
Number of available for sale securities	28	3
Securities Available For Sale, Less than 12 Months, Fair Value	389,989	47,174
Securities Available For Sale, Less than 12 Months, Unrealized Losses	(18,644)	(228)
Securities Available For Sale, 12 Months or More, Fair Value	34,229
Securities Available For Sale, 12 Months or More, Unrealized Losses	(2,150)
Securities Available For Sale, Fair Value, Total	424,218	47,174
Securities Available For Sale, Unrealized Losses, Total	(20,794)	(228)
Number of held to maturity securities	21
Securities Held To Maturity, Less than 12 Months, Fair Value	301,312
Securities Held To Maturity, Less than 12 Months, Unrealized Losses	(15,844)
Securities Held To Maturity, Greater than 12 Months, Fair Value
Securities Held To Maturity, Greater than 12 Months, Unrealized Losses
Securities Held To Maturity, Fair Value, Total	301,312
Securities Held To Maturity, Unrealized Losses, Total	(15,844)		(11)
Agency Collateralized Mortgage Obligations [Member] | Less than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	21
Agency Collateralized Mortgage Obligations [Member] | Greater than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities
States of the U.S. and Political Subdivisions [Member]
Schedule Of Securities [Line Items]
Number of available for sale securities, Less than 1 year	2
Number of available for sale securities, Greater than 1 year
Number of available for sale securities	2
Securities Available For Sale, Less than 12 Months, Fair Value	3,022
Securities Available For Sale, Less than 12 Months, Unrealized Losses	(250)
Securities Available For Sale, 12 Months or More, Fair Value
Securities Available For Sale, 12 Months or More, Unrealized Losses
Securities Available For Sale, Fair Value, Total	3,022
Securities Available For Sale, Unrealized Losses, Total	(250)
Number of held to maturity securities	27
Securities Held To Maturity, Less than 12 Months, Fair Value	31,537
Securities Held To Maturity, Less than 12 Months, Unrealized Losses	(2,022)
Securities Held To Maturity, Greater than 12 Months, Fair Value
Securities Held To Maturity, Greater than 12 Months, Unrealized Losses
Securities Held To Maturity, Fair Value, Total	31,537
Securities Held To Maturity, Unrealized Losses, Total	(2,022)
States of the U.S. and Political Subdivisions [Member] | Less than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	27
States of the U.S. and Political Subdivisions [Member] | Greater than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities
Collateralized Debt Obligations [Member]
Schedule Of Securities [Line Items]
Number of available for sale securities, Less than 1 year		7
Number of available for sale securities, Greater than 1 year	8	9
Number of available for sale securities	8	16
Securities Available For Sale, Less than 12 Months, Fair Value		8,708
Securities Available For Sale, Less than 12 Months, Unrealized Losses		(909)
Securities Available For Sale, 12 Months or More, Fair Value	7,965	5,532
Securities Available For Sale, 12 Months or More, Unrealized Losses	(10,115)	(12,367)
Securities Available For Sale, Fair Value, Total	7,965	14,240
Securities Available For Sale, Unrealized Losses, Total	(10,115)	(13,276)
Number of held to maturity securities		1
Securities Held To Maturity, Less than 12 Months, Fair Value
Securities Held To Maturity, Less than 12 Months, Unrealized Losses
Securities Held To Maturity, Greater than 12 Months, Fair Value		477
Securities Held To Maturity, Greater than 12 Months, Unrealized Losses		(35)
Securities Held To Maturity, Fair Value, Total		477
Securities Held To Maturity, Unrealized Losses, Total		(35)	(314)
Collateralized Debt Obligations [Member] | Less than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities
Collateralized Debt Obligations [Member] | Greater than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities		1
Other Debt Securities [Member]
Schedule Of Securities [Line Items]
Number of available for sale securities, Less than 1 year
Number of available for sale securities, Greater than 1 year	4	4
Number of available for sale securities	4	4
Securities Available For Sale, Less than 12 Months, Fair Value
Securities Available For Sale, Less than 12 Months, Unrealized Losses
Securities Available For Sale, 12 Months or More, Fair Value	5,950	5,899
Securities Available For Sale, 12 Months or More, Unrealized Losses	(929)	(972)
Securities Available For Sale, Fair Value, Total	5,950	5,899
Securities Available For Sale, Unrealized Losses, Total	(929)	(972)
Securities Held To Maturity, Unrealized Losses, Total			(181)
Equity securities [Member]
Schedule Of Securities [Line Items]
Number of available for sale securities, Less than 1 year		1
Number of available for sale securities, Greater than 1 year
Number of available for sale securities		1
Securities Available For Sale, Less than 12 Months, Fair Value		654
Securities Available For Sale, Less than 12 Months, Unrealized Losses		(9)
Securities Available For Sale, 12 Months or More, Fair Value
Securities Available For Sale, 12 Months or More, Unrealized Losses
Securities Available For Sale, Fair Value, Total		654
Securities Available For Sale, Unrealized Losses, Total		(9)
Non-Agency Collateralized Mortgage Obligations [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	3
Securities Held To Maturity, Less than 12 Months, Fair Value	2,010
Securities Held To Maturity, Less than 12 Months, Unrealized Losses	(4)
Securities Held To Maturity, Greater than 12 Months, Fair Value
Securities Held To Maturity, Greater than 12 Months, Unrealized Losses
Securities Held To Maturity, Fair Value, Total	2,010
Securities Held To Maturity, Unrealized Losses, Total	(4)		(1,373)
Non-Agency Collateralized Mortgage Obligations [Member] | Less than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	3
Non-Agency Collateralized Mortgage Obligations [Member] | Greater than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities
Commercial Mortgage-Backed Securities [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	1
Securities Held To Maturity, Less than 12 Months, Fair Value	984
Securities Held To Maturity, Less than 12 Months, Unrealized Losses	(37)
Securities Held To Maturity, Greater than 12 Months, Fair Value
Securities Held To Maturity, Greater than 12 Months, Unrealized Losses
Securities Held To Maturity, Fair Value, Total	984
Securities Held To Maturity, Unrealized Losses, Total	$ (37)
Commercial Mortgage-Backed Securities [Member] | Less than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	1
Commercial Mortgage-Backed Securities [Member] | Greater than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities