Components of deferred tax assets and liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Deferred Tax Assets Gross Abstract
Deferred Tax Assets Tax Credit Carryforwards Other	$ 6,200	$ 2,666
Deferred Tax Asset Operating Loss Carryforwards And Other Carryforwards	1,345,667	1,201,174
Deferred Tax Assets Tax Deferred Expense Compensation And Benefits	133,279	97,276
Allowance for loan losses	721,114	592,664
Deferred Tax Assets Depreciation	6,901	6,699
Other temporary differences	39,576	31,864
Total gross deferred tax assets	2,273,713	1,953,341
Deferred Tax Liabilities Abstract
Deferred Tax Liabilities Deferred Expense Deferred Policy Acquisition Cost	38,737	37,281
Deferred Tax Liabilities Parents Basis In Discontinued Operation	2,795	6,400
FDIC-assisted transaction	72,537	53,351
Deferred Tax Liabilities, Investments	20,784	51,002
Other temporary differences	10,402	10,142
Total gross deferred tax liabilities	145,255	161,635
Valuation allowance	1,268,954	1,260,542
Net deferred tax asset	859,504	531,164
Loans Member
Deferred Tax Assets Gross Abstract
Deferred Tax Assets Deferred Income	7,740	6,579
Deferred Tax Liabilities Abstract
Deferred Tax Liabilities Deferred Expense Deferred Financing Costs	0	3,459
Gains Losses On Sales Of Assets Member
Deferred Tax Assets Gross Abstract
Deferred Tax Assets Deferred Income	9,910	10,528
Intercompany [Member]
Deferred Tax Assets Gross Abstract
Deferred Tax Assets Deferred Income	$ 3,326	$ 3,891