Components of deferred tax assets and liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Deferred Tax Assets Gross Abstract
Deferred Tax Assets Tax Credit Carryforwards Other	$ 3,139	$ 3,459
Deferred Tax Asset Operating Loss Carryforwards And Other Carryforwards	1,186,297	1,174,488
Deferred Tax Assets Tax Deferred Expense Compensation And Benefits	103,118	104,663
Allowance for loan losses	595,494	605,105
Deferred Tax Assets Depreciation	5,627	5,527
Other temporary differences	28,470	27,341
Total gross deferred tax assets	1,944,688	1,943,478
Deferred Tax Liabilities Abstract
Deferred Tax Liabilities Deferred Expense Deferred Policy Acquisition Cost	33,524	32,293
Deferred Tax Liabilities Parents Basis In Discontinued Operation	20,721	20,721
FDIC-assisted transaction	145,628	142,000
Deferred Tax Liabilities Other Comprehensive Income	72,223	73,991
Deferred Tax Liabilities Deferred Expense Deferred Financing Costs	4,224	4,277
Other temporary differences	8,262	6,187
Total gross deferred tax liabilities	284,582	279,469
Valuation allowance	1,260,099	1,259,358
Net deferred tax asset	400,007	404,651
Loans
Deferred Tax Assets Gross Abstract
Deferred Tax Assets Deferred Income	7,035	6,788
Gains Losses On Sales Of Assets Member
Deferred Tax Assets Gross Abstract
Deferred Tax Assets Deferred Income	11,454	11,763
Intercompany [Member]
Deferred Tax Assets Gross Abstract
Deferred Tax Assets Deferred Income	$ 4,054	$ 4,344