Components of deferred tax assets and liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Deferred Tax Assets Gross Abstract
Deferred Tax Assets Tax Credit Carryforwards Other	$ 3,633	$ 3,459
Deferred Tax Asset Operating Loss Carryforwards And Other Carryforwards	1,195,338	1,174,488
Deferred Tax Assets Tax Deferred Expense Compensation And Benefits	102,796	104,663
Allowance for loan losses	599,030	605,105
Deferred Tax Assets Depreciation	5,798	5,527
Other temporary differences	35,972	27,661
Total gross deferred tax assets	1,964,008	1,943,798
Deferred Tax Liabilities Abstract
Deferred Tax Liabilities Deferred Expense Deferred Policy Acquisition Cost	35,906	32,293
Deferred Tax Liabilities Parents Basis In Discontinued Operation	8,155	20,721
FDIC-assisted transaction	57,293	142,000
Deferred Tax Liabilities Other Comprehensive Income	55,833	73,991
Deferred Tax Liabilities Deferred Expense Deferred Financing Costs	3,273	4,277
Other temporary differences	7,252	6,507
Total gross deferred tax liabilities	167,712	279,789
Valuation allowance	1,261,594	1,259,358
Net deferred tax asset	534,702	404,651
Loans Member
Deferred Tax Assets Gross Abstract
Deferred Tax Assets Deferred Income	6,813	6,788
Gains Losses On Sales Of Assets Member
Deferred Tax Assets Gross Abstract
Deferred Tax Assets Deferred Income	10,836	11,763
Intercompany [Member]
Deferred Tax Assets Gross Abstract
Deferred Tax Assets Deferred Income	$ 3,792	$ 4,344