Quantitative inputs level 3 (Detail) (USD $) In Thousands, unless otherwise specified											3 Months Ended								3 Months Ended			3 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2012 Fair Value, Measurements, Recurring [Member]	Dec. 31, 2011 Fair Value, Measurements, Recurring [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member]		Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member]		Sep. 30, 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]	Sep. 30, 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]	Sep. 30, 2012 Servicing Asset At Fair Value Amount [Member] Fair Value Inputs Level 3 Internal Valuation Technique [Member] Fair Value, Measurements, Recurring [Member]	Sep. 30, 2012 Loan Fair Value Inputs Level 3 Internal Valuation Technique [Member] Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2012 Loans Held For Sale [Member] Fair Value Inputs Level 3 Internal Valuation Technique [Member] Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2012 Real Estate Acquired in Satisfaction of Debt [Member] Fair Value Inputs Level 3 Internal Valuation Technique [Member] Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2012 Collateralized Mortgage Obligations Member Fair Value, Measurements, Recurring [Member]	Dec. 31, 2011 Collateralized Mortgage Obligations Member Fair Value, Measurements, Recurring [Member]	Sep. 30, 2012 Collateralized Mortgage Obligations Member Trading Account Assets[Member] Fair Value Inputs Level 3 Internal Valuation Technique [Member] Fair Value, Measurements, Recurring [Member]	Sep. 30, 2012 Other Securities [Member] Fair Value, Measurements, Recurring [Member]	Dec. 31, 2011 Other Securities [Member] Fair Value, Measurements, Recurring [Member]	Sep. 30, 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					$ 5,120,301	$ 5,009,823														$ 24,878	$ 24,962
Trading Account Assets Fair Value Disclosure					226,916	436,330											3,342	3,545	2,634	17,899	17,248	1,245
Servicing Asset At Fair Value Amount	158,367	151,323	157,226	166,907	158,367	151,323							158,367
Loans Receivable, Fair Value Disclosure							11,887	[1]	109,694	[1]				11,887
Loans Held-for-sale, Fair Value Disclosure							102,092	[2]	84,368	[2]					102,092
Real Estate Acquired Through Foreclosure							93,560	[3]	23,735	[4]						93,560
Liabilities Fair Value Disclosure Abstract
Business Acquisition, Contingent Consideration, at Fair Value					$ (103,688)	$ (99,762)					$ (103,688)
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	Discounted cash flow model
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	Weighted average life Net loss rate	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													11.5 years (3.8 - 47.3 years)		2.0				2.7 years (0.4 - 6.7 years)			5.7
Fair Value Inputs Prepayment Rate																						9.00%
Fair Value Inputs Prepayment Weighted Average And Range													8.7% (2.1% - 26.5%)						23.4% (18.0% - 28.8%)
Fair Value Inputs Yield																			3.7% (0.8% - 4.7%)			12.8
Fair Value Inputs Credit Loss Rate											23.2% (0.0% - 100.0%)
Fair Value Inputs Discount Rate Percentage												5.30%
Fair Value Inputs Haircut External Appraisal														19.9% (5.0% - 30.0%)		22.9% (5.0% - 40.0%)
Fair Value Inputs Discount Rate													12.0% (10.0 - 15.5%)
Fair Value Net Loss Rate															49.6%

[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] Relates to lower of cost or fair value adjustments on loans held-for-sale and loans transferred from loans held-in-portfolio to loans held-for-sale.

[3] 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 $6 million at September 30, 2012.

[4] 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 $2 million at September 30, 2011.