Quantitative inputs level 3 (Detail) (USD $) In Thousands, unless otherwise specified												3 Months Ended									3 Months Ended				3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010	Mar. 31, 2012 Fair Value, Measurements, Recurring [Member]	Dec. 31, 2011 Fair Value, Measurements, Recurring [Member]	Mar. 31, 2011 Fair Value, Measurements, Recurring [Member]	Mar. 31, 2012 Fair Value, Measurements, Nonrecurring [Member]		Mar. 31, 2011 Fair Value, Measurements, Nonrecurring [Member]		Mar. 31, 2012 Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Contingent Liability [Member] Fair Value, Measurements, Recurring [Member]	Mar. 31, 2012 Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Contingent Liability [Member] Fair Value Inputs Level 3 Internal Valuation Technique [Member] Fair Value, Measurements, Recurring [Member]	Mar. 31, 2012 Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Contingent Liability [Member] Fair Value Inputs Level 3 Internal Valuation Technique [Member] Fair Value, Measurements, Recurring [Member] Risk Premium [Member]	Mar. 31, 2012 Servicing Asset At Fair Value Amount [Member] Fair Value Inputs Level 3 Internal Valuation Technique [Member] Fair Value, Measurements, Recurring [Member]	Mar. 31, 2012 Loan Fair Value Inputs Level 3 Internal Valuation Technique [Member] Fair Value, Measurements, Nonrecurring [Member]	Mar. 31, 2012 Real Estate Acquired in Satisfaction of Debt [Member] Fair Value Inputs Level 3 Internal Valuation Technique [Member] Fair Value, Measurements, Nonrecurring [Member]	Mar. 31, 2012 Collateralized Mortgage Obligations Member Fair Value, Measurements, Recurring [Member]	Dec. 31, 2011 Collateralized Mortgage Obligations Member Fair Value, Measurements, Recurring [Member]	Mar. 31, 2011 Collateralized Mortgage Obligations Member Fair Value, Measurements, Recurring [Member]	Mar. 31, 2012 Collateralized Mortgage Obligations Member Trading Account Assets[Member] Fair Value Inputs Level 3 Internal Valuation Technique [Member] Fair Value, Measurements, Recurring [Member]	Mar. 31, 2012 Other Securities [Member] Fair Value, Measurements, Recurring [Member]	Dec. 31, 2011 Other Securities [Member] Fair Value, Measurements, Recurring [Member]	Mar. 31, 2011 Other Securities [Member] Fair Value, Measurements, Recurring [Member]	Mar. 31, 2012 Other Securities [Member] Trading Account Assets[Member] Fair Value Inputs Level 3 Internal Valuation Technique [Member] Fair Value, Measurements, Recurring [Member]
Assets
Available For Sale Securities Fair Value Disclosure					$ 5,138,616	$ 5,009,823	$ 5,686,341															$ 26,440	$ 24,962	$ 27,608
Trading Account Assets Fair Value Disclosure					404,206	436,330	633,641											3,484	3,545	3,391	2,750	20,360	17,248	21,015	1,325
Servicing Asset At Fair Value Amount	156,331	151,323	167,416	166,907	156,331	151,323	167,416								156,331
Loans Receivable, Fair Value Disclosure								50,000	[1]	19,000	[1]					49,876
Real Estate Acquired Through Foreclosure								77,000	[2]	13,000	[2]						76,648
Liabilities Fair Value Disclosure Abstract
Business Acquisition, Contingent Consideration, at Fair Value					$ (100,834)	$ (99,762)	$ (94,483)						$ (100,834)
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Abstract]
Fair Value, Trading Account Assets, Valuation Techniques																					Discounted cash flow model				Discounted cash flow model
Fair Value, Servicing Rights, Valuation Techniques															Discounted cash flow model
Fair Value, Assets Held-for-sale, Long Lived, Valuation Techniques																External Appraisal
Fair Value Assets Measuredon Nonrecurring Basis Valuation Techniques Impaired Loans																	External Appraisal
Fair Value, Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Abstract]
Fair Value, Other Liabilities, Valuation Techniques													Discounted model cash flow
Unobservable Inputs													Credit loss rate on covered loans of discount rate Risk premium component		Prepayment speed Weighted average life Discount rate	Haircut applied on external appraisals	Haircut applied on external appraisals				Weighted average life Yield Constant prepayment rate				Weighted average life Yield Constant prepayment rate
Fair Value Inputs Quantitative Information [Abstract]
Fair Value Inputs Weighted Average Life And Range															12.7 years (4.0 - 24.0 years)						2.4 years (0.4 - 3.4 years)				5.8
Fair Value Inputs Prepayment Rate																									9.00%
Fair Value Inputs Prepayment Weighted Average And Range															7.9% (4.2% - 24.7%)						24.2% (19.5% - 28.0%)
Fair Value Inputs Yield																					4.15				12.9
Fair Value Inputs Credit Loss Rate													27.4% (0.0% - 100.0%)
Fair Value Inputs Discount Rate Percentage												6.60%		4.80%
Fair Value Inputs Haircut External Appraisal																25.3% (5.0% - 48.0%)	19.1% (5.0% - 40.0%)
Fair Value Inputs Discount Rate															12.1% (10.0 - 15.5%)

[1] Relates mostly to certain impaired collateral dependent loans. The impairment was measured based on the fair value of the collateral, which is derived from appraisals that take into consideration prices in observed transactions involving similar assets in similar locations, in accordance with the provisions of ASC Section 310-10-35.

[2] Represents the fair value of foreclosed real estate and other collateral owned that were written down to their fair value. Costs to sell excluded from the reported fair value amount were $5 million at March 31, 2012 and $1 million at March 31, 2011.