Investment Securities - Additional Information (Detail) (USD $)	12 Months Ended										12 Months Ended			12 Months Ended					12 Months Ended		3 Months Ended	12 Months Ended						12 Months Ended
	Dec. 31, 2013 Securities	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Wells Fargo [Member]	Dec. 31, 2013 SunTrust Bank [Member]	Dec. 31, 2013 Royal Bank of Scotland [Member]	Dec. 31, 2013 Split Rated [Member]	Dec. 31, 2013 Below Investment Grade [Member]	Dec. 31, 2013 Marketable Equity Securities [Member] Securities	Dec. 31, 2012 Marketable Equity Securities [Member]	Dec. 31, 2013 Residential Mortgage-Backed Securities, Non-agency [Member]	Dec. 31, 2012 Residential Mortgage-Backed Securities, Non-agency [Member]	Dec. 31, 2013 Single Issue Trust Preferred [Member] Below Investment Grade [Member]	Dec. 31, 2013 U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]	Dec. 31, 2012 U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]	Dec. 31, 2013 Commercial Mortgage-Backed Securities Agency [Member]	Dec. 31, 2013 Residential Mortgage-Backed Securities, Agency [Member]	Dec. 31, 2012 Residential Mortgage-Backed Securities, Agency [Member]	Dec. 31, 2013 Originated Prior to 2005 [Member]	Dec. 31, 2013 Originated in 2006 and 2007 [Member]	Dec. 31, 2013 TRUP CDOs [Member]	Dec. 31, 2013 TRUP CDOs [Member] Securities	Dec. 31, 2012 TRUP CDOs [Member]	Dec. 31, 2013 TRUP CDOs [Member] Likely Sold Four Securities [Member]	Dec. 31, 2013 TRUP CDOs [Member] Split Rated [Member]	Dec. 31, 2013 TRUP CDOs [Member] Below Investment Grade [Member]	Dec. 31, 2013 TRUP CDOs [Member] Investment Grade [Member]	Dec. 31, 2013 Mortgage Backed Securities [Member]	Dec. 31, 2012 Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Gross unrealized losses on available for sale securities	$ 44,003,000	$ 58,717,000							$ 1,000	$ 531,000	$ 0	$ 458,000		$ 748,000	$ 52,000	$ 8,740,000	$ 1,815,000	$ 0
Available for sale securities in unrealized loss position	89
Available for sale securities in portfolio, number	281
Amortized cost agency residential mortgage securities	813,049,000	673,315,000							3,299,000	6,660,000	16,369,000	24,569,000		172,324,000	336,747,000	241,947,000	215,788,000	101,769,000
Amortized cost									3,300,000		16,370,000
Amortized cost above investment grade											6,310,000
Amortized cost below investment grade											10,060,000
Percentage of portfolio of non-agency mortgage backed securities with collateral																			47.00%	53.00%
Credit-related other-than-temporary impairment recognized in earnings											0.00										6,360,000	7,200,000	5,970,000
Noncredit-related other-than-temporary impairment recognized in accumulated other comprehensive income (loss)											0										5,220,000	12,220,000	7,940,000
Capitalization of banks, equal to or greater than, in the single-issue trust preferred portfolio	10,000,000,000
Number of trust preferred securities deferring interest payments	2
Amortized cost of trust preferred securities	632,000			9,900,000	7,390,000	972,000
Defer interest payments, maximum period	5 years
Amortized cost of available for sale single issue trust preferred securities							2,980,000	11,230,000
Amortized cost of available for sale TRUP CDOs and single issue trust preferred securities in an unrealized loss position 12 months or longer													10,230,000												5,000,000
Period of general widening in overall risk premiums	4 years
Credit-related other-than-temporary impairment																						4,030,000		2,330,000
Issue of Trup Cdos securities																						4
Issue of Additional Trup Cdos securities																						1
Excluded Trup Cdos securities																						5
Noncredit related other-than-temporary impairment, net of deferred taxes																					3,390,000
Noncredit-related other-than-temporary impairment recognized																					34,300,000	34,300,000	46,520,000
Amortized cost of available for sale TRUP CDOs and single issue trust preferred securities in an unrealized loss position 12 months or longer																										62,280,000	6,580,000
New issuance of Preferred Stock estimated	60,000,000,000
Recognized cumulative credit-related other-than-temporary impairment	860,000	4,955,000	20,958,000
Other-than-temporarily impaired, the collateralization ratios low	93.60%
Other-than-temporarily impaired, the collateralization ratios high	209.20%
Other-than-temporarily impaired, the collateralization ratios median	133.40%
Other-than-temporarily impaired, the collateralization ratios weighted average	158.97%
Security other-than-temporarily impaired	100.00%
Number of equity securities other-than-temporarily impaired									0
Available-for-sale securities amortized cost	813,049,000																											474,104,000
Available-for-sale securities estimated fair value	775,284,000	625,625,000							3,870,000	6,386,000	16,532,000	25,045,000		171,754,000	337,522,000	233,432,000	216,464,000	106,510,000										466,428,000
Held-to-maturity securities amortized cost	40,965,000	43,467,000												10,762,000	10,916,000		50,000	61,000										50,000
Held-to-maturity securities estimated fair value	38,293,000	42,695,000												12,451,000	13,416,000		59,000	71,000										59,000
Carrying value of securities pledged	640,870,000	569,680,000
Mortgage backed securities net unrealized gains																												$ 7,667,000	$ 5,227,000
Aggregate book value percentage of securities to shareholders' equity														10.00%