Condensed Consolidating Statement of Condition (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013	Mar. 31, 2013		Dec. 31, 2012
Assets
Cash And Due From Banks	$ 387,917		$ 423,211	$ 242,290		$ 439,363
Money market investments	1,622,433		858,453
Trading Securities	359,247		339,743
Available For Sale Securities	5,768,890		5,294,800
Investment securities held-to-maturity, at amortized cost	139,019		140,496
Other investment securities, at lower of cost or realizable value	166,556		181,752
Loans held-for-sale, at lower of cost or fair value	94,877		110,426
Loans held-in-portfolio:
Loans held-in-portfolio	21,703,050		21,704,010
Covered Loans	2,870,054		2,984,427
Less- Unearned Income	91,273		92,144
Allowance for loan losses	640,348		640,555
Total loans held-in-portfolio, net	23,841,483		23,955,738
FDIC loss share asset	833,721		948,608	1,380,592		1,399,098
Premises and equipment, net	513,855		519,516
Interest Receivable	125,895		131,536
Servicing Asset At Fair Value Amount	156,529		161,099	153,949		154,430
Other Assets	1,747,646		1,687,558
Goodwill	647,757		647,757	647,757		647,757
Intangible Assets Net Excluding Goodwill	42,625		45,132
Total assets	36,744,162		35,749,333
Deposits Abstract
Noninterest Bearing Deposit Liabilities	6,326,596		5,922,682
Interest Bearing Deposit Liabilities	20,939,055		20,788,463
Total deposits	27,265,651		26,711,145
Federal Funds Purchased and Securities Sold Under Agreements To Repurchase	2,208,213		1,659,292
Other short-term borrowings	1,200		401,200
Notes Payable	1,506,408		1,584,754
Other liabilities	1,016,943		766,792
Liabilities	31,998,415		31,123,183
Stockholders Equity Abstract
Preferred stock	50,160		50,160
Common stock	1,035		1,034
Surplus	4,171,817		4,170,152
Accumulated deficit	679,908		594,430
Treasury stock	(898)		(881)
Accumulated other comprehensive (loss) income, net of tax	(156,275)	[1]	(188,745)	(122,008)	[1]
Total stockholders' equity	4,745,747		4,626,150	3,971,143		4,110,000
Liabilities And Stockholders Equity	36,744,162		35,749,333
Non Covered Under Loss Sharing Agreements With F D I C [Member]
Loans held-in-portfolio:
Real Estate Acquired Through Foreclosure	136,965		135,501
Covered Under Loss Sharing Agreements With F D I C [Member]
Loans held-in-portfolio:
Covered Loans	2,870,054		2,984,427
Real Estate Acquired Through Foreclosure	158,747		168,007
Parent Company [Member]
Assets
Cash And Due From Banks	2,305		10,595	4,939		1,103
Money market investments	29,913		18,721
Trading Securities	1,460		1,353
Available For Sale Securities	204		204
Investment securities held-to-maturity, at amortized cost	0		0
Other investment securities, at lower of cost or realizable value	10,850		10,850
Investment in subsidiaries	4,997,798		4,856,566
Loans held-for-sale, at lower of cost or fair value	0		0
Loans held-in-portfolio:
Loans held-in-portfolio	493,115		521,092
Covered Loans	0		0
Less- Unearned Income	0		0
Allowance for loan losses	5		304
Total loans held-in-portfolio, net	493,110		520,788
FDIC loss share asset	0		0
Premises and equipment, net	2,037		2,135
Interest Receivable	122		64
Servicing Asset At Fair Value Amount	0		0
Other Assets	68,752		66,577
Goodwill	0		0
Intangible Assets Net Excluding Goodwill	554		554
Total assets	5,607,105		5,488,407
Deposits Abstract
Noninterest Bearing Deposit Liabilities	0		0
Interest Bearing Deposit Liabilities	0		0
Total deposits	0		0
Federal Funds Purchased and Securities Sold Under Agreements To Repurchase	0		0
Other short-term borrowings	0		0
Notes Payable	822,616		822,351
Subordinated Debt	0		0
Other liabilities	38,742		39,906
Liabilities	861,358		862,257
Stockholders Equity Abstract
Preferred stock	50,160		50,160
Common stock	1,035		1,034
Surplus	4,163,290		4,161,625
Accumulated deficit	688,435		602,957
Treasury stock	(898)		(881)
Accumulated other comprehensive (loss) income, net of tax	(156,275)		(188,745)
Total stockholders' equity	4,745,747		4,626,150
Liabilities And Stockholders Equity	5,607,105		5,488,407
Parent Company [Member] | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Loans held-in-portfolio:
Real Estate Acquired Through Foreclosure	0		0
Parent Company [Member] | Covered Under Loss Sharing Agreements With F D I C [Member]
Loans held-in-portfolio:
Real Estate Acquired Through Foreclosure	0		0
Non Guarantor Subsidiaries Member
Assets
Cash And Due From Banks	614		616	622		624
Money market investments	817		4,804
Trading Securities	0		0
Available For Sale Securities	0		0
Investment securities held-to-maturity, at amortized cost	0		0
Other investment securities, at lower of cost or realizable value	4,492		4,492
Investment in subsidiaries	1,719,972		1,670,809
Loans held-for-sale, at lower of cost or fair value	0		0
Loans held-in-portfolio:
Loans held-in-portfolio	0		0
Covered Loans	0		0
Less- Unearned Income	0		0
Allowance for loan losses	0		0
Total loans held-in-portfolio, net	0		0
FDIC loss share asset	0		0
Premises and equipment, net	0		0
Interest Receivable	31		114
Servicing Asset At Fair Value Amount	0		0
Other Assets	27,165		19,407
Goodwill	0		0
Intangible Assets Net Excluding Goodwill	0		0
Total assets	1,753,091		1,700,242
Deposits Abstract
Noninterest Bearing Deposit Liabilities	0		0
Interest Bearing Deposit Liabilities	0		0
Total deposits	0		0
Federal Funds Purchased and Securities Sold Under Agreements To Repurchase	0		0
Other short-term borrowings	41,319		0
Notes Payable	149,663		149,663
Subordinated Debt	0		0
Other liabilities	4,904		39,245
Liabilities	195,886		188,908
Stockholders Equity Abstract
Preferred stock	0		0
Common stock	2		2
Surplus	4,479,208		4,479,208
Accumulated deficit	(2,906,205)		(2,940,509)
Treasury stock	0		0
Accumulated other comprehensive (loss) income, net of tax	(15,800)		(27,367)
Total stockholders' equity	1,557,205		1,511,334
Liabilities And Stockholders Equity	1,753,091		1,700,242
Non Guarantor Subsidiaries Member | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Loans held-in-portfolio:
Real Estate Acquired Through Foreclosure	0		0
Non Guarantor Subsidiaries Member | Covered Under Loss Sharing Agreements With F D I C [Member]
Loans held-in-portfolio:
Real Estate Acquired Through Foreclosure	0		0
Other Subsidiaries [Member]
Assets
Cash And Due From Banks	387,922		422,967	242,344		439,552
Money market investments	1,603,720		839,732
Trading Securities	357,787		338,390
Available For Sale Securities	5,768,686		5,294,596
Investment securities held-to-maturity, at amortized cost	139,019		140,496
Other investment securities, at lower of cost or realizable value	151,214		166,410
Investment in subsidiaries	0		0
Loans held-for-sale, at lower of cost or fair value	94,877		110,426
Loans held-in-portfolio:
Loans held-in-portfolio	21,701,254		21,702,418
Covered Loans	2,870,054		2,984,427
Less- Unearned Income	91,273		92,144
Allowance for loan losses	640,343		640,251
Total loans held-in-portfolio, net	23,839,692		23,954,450
FDIC loss share asset	833,721		948,608
Premises and equipment, net	511,818		517,381
Interest Receivable	125,803		131,368
Servicing Asset At Fair Value Amount	156,529		161,099
Other Assets	1,666,806		1,642,760
Goodwill	647,758		647,757
Intangible Assets Net Excluding Goodwill	42,071		44,578
Total assets	36,623,135		35,664,526
Deposits Abstract
Noninterest Bearing Deposit Liabilities	6,329,520		5,933,649
Interest Bearing Deposit Liabilities	20,939,872		20,793,267
Total deposits	27,269,392		26,726,916
Federal Funds Purchased and Securities Sold Under Agreements To Repurchase	2,219,413		1,659,292
Other short-term borrowings	451,200		920,700
Notes Payable	534,129		612,740
Subordinated Debt	0		0
Other liabilities	988,890		728,899
Liabilities	31,463,024		30,648,547
Stockholders Equity Abstract
Preferred stock	0		0
Common stock	56,079		56,079
Surplus	6,057,474		6,056,774
Accumulated deficit	(798,325)		(907,972)
Treasury stock	0		0
Accumulated other comprehensive (loss) income, net of tax	(155,117)		(188,902)
Total stockholders' equity	5,160,111		5,015,979
Liabilities And Stockholders Equity	36,623,135		35,664,526
Other Subsidiaries [Member] | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Loans held-in-portfolio:
Real Estate Acquired Through Foreclosure	136,965		135,501
Other Subsidiaries [Member] | Covered Under Loss Sharing Agreements With F D I C [Member]
Loans held-in-portfolio:
Real Estate Acquired Through Foreclosure	158,747		168,007
Consolidation Eliminations Member
Assets
Cash And Due From Banks	(2,924)		(10,967)	(5,615)		(1,916)
Money market investments	(12,017)		(4,804)
Trading Securities	0		0
Available For Sale Securities	0		0
Investment securities held-to-maturity, at amortized cost	0		0
Other investment securities, at lower of cost or realizable value	0		0
Investment in subsidiaries	(6,717,770)		(6,527,375)
Loans held-for-sale, at lower of cost or fair value	0		0
Loans held-in-portfolio:
Loans held-in-portfolio	(491,319)		(519,500)
Covered Loans	0		0
Less- Unearned Income	0		0
Allowance for loan losses	0		0
Total loans held-in-portfolio, net	(491,319)		(519,500)
FDIC loss share asset	0		0
Premises and equipment, net	0		0
Interest Receivable	(61)		(10)
Servicing Asset At Fair Value Amount	0		0
Other Assets	(15,077)		(41,186)
Goodwill	(1)		0
Intangible Assets Net Excluding Goodwill	0		0
Total assets	(7,239,169)		(7,103,842)
Deposits Abstract
Noninterest Bearing Deposit Liabilities	(2,924)		(10,967)
Interest Bearing Deposit Liabilities	(817)		(4,804)
Total deposits	(3,741)		(15,771)
Federal Funds Purchased and Securities Sold Under Agreements To Repurchase	(11,200)		0
Other short-term borrowings	(491,319)		(519,500)
Notes Payable	0		0
Subordinated Debt	0		0
Other liabilities	(15,593)		(41,258)
Liabilities	(521,853)		(576,529)
Stockholders Equity Abstract
Preferred stock	0		0
Common stock	(56,081)		(56,081)
Surplus	(10,528,155)		(10,527,455)
Accumulated deficit	3,696,003		3,839,954
Treasury stock	0		0
Accumulated other comprehensive (loss) income, net of tax	170,917		216,269
Total stockholders' equity	(6,717,316)		(6,527,313)
Liabilities And Stockholders Equity	(7,239,169)		(7,103,842)
Consolidation Eliminations Member | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Loans held-in-portfolio:
Real Estate Acquired Through Foreclosure	0		0
Consolidation Eliminations Member | Covered Under Loss Sharing Agreements With F D I C [Member]
Loans held-in-portfolio:
Real Estate Acquired Through Foreclosure	$ 0		$ 0

[1] All amounts presented are net of tax.