Components of Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Deferred tax assets:
Tax credits available for carryforward	$ 3,423	$ 5,833
Net operating loss and other carryforward available	1,112,849	1,222,717
Postretirement and pension benefits	92,934	131,508
Allowance for loan losses	554,187	393,289
Accelerated depreciation	6,850	7,108
Other temporary differences	20,074	26,063
Total gross deferred tax assets	1,814,357	1,813,376
Deferred tax liabilities:
Differences between the assigned values and the tax bases of assets and liabilities recognized in purchase business combinations	30,447	31,846
Difference in outside basis between financial and tax reporting on sale of a business	11,809	11,120
FDIC-assisted transaction	94,931	64,049
Unrealized net gain on trading and available-for-sale securities	63,192	52,186
Deferred loan origination costs	4,669	6,911
Other temporary differences	3,330	1,392
Total gross deferred tax liabilities	208,378	167,504
Valuation allowance	1,257,619	1,268,589
Net deferred tax asset	348,360	377,283
Loans
Deferred tax assets:
Deferred income	6,842	8,322
Gains (Losses) on Sales of Assets
Deferred tax assets:
Deferred income	12,376	13,056
Intercompany
Deferred tax assets:
Deferred income	$ 4,822	$ 5,480