Fair Value Disclosures (Quantitative Information about Level 3 Fair Value Measurements) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Non-Agency Residential Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	$ 25,592
Valuation Technique(s)	Discounted Cash Flow
Conditional repayment rate	10.30%
Loss severity	43.00%
Conditional default rate	3.80%
Other Structured Financial Products [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	9,977
Valuation Technique(s)	Discounted Cash Flow
Credit default rates, call options and deferrals, waterfall structure, and covenants.	Varies by individual security, refer to Note 3
Other Equity Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	3,157
Valuation Technique(s)	Discounted Cash Flow
Other Equity Securities [Member] | Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Price to book multiple	0.2
Other Equity Securities [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Price to book multiple	1.5
Other Equity Securities [Member] | Weighted Average [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Price to book multiple	0.9
Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	69,443
Valuation Technique(s)	Discounted Cash Flow
Impaired Loans [Member] | Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Timing of cash flows based upon current discount rates and terminal value	1.50%
Impaired Loans [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Timing of cash flows based upon current discount rates and terminal value	6.90%
Impaired Loans [Member] | Weighted Average [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Timing of cash flows based upon current discount rates and terminal value	4.00%
Foreclosed Assets [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	$ 22,557
Valuation Technique(s)	Discounted Cash Flow
Foreclosed Assets [Member] | Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Third party appraisals less estimated selling costs	0.00%
Foreclosed Assets [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Third party appraisals less estimated selling costs	100.00%
Foreclosed Assets [Member] | Weighted Average [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Third party appraisals less estimated selling costs	25.10%