Basis Of Presentation And Accounting Policies (Valuation Methodologies For Instruments Measured At Fair Value On Nonrecurring Basis) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Covered loans	$ 546,234	$ 571,489	$ 595,428
Fair Value Measurements on a Nonrecurring Basis
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Impaired loans carried at fair value	50,437	70,296	58,648
Other real estate owned	37,325	46,680	50,866
Covered loans	546,234	571,489	595,428
Covered other real estate owned	88,895	78,617	81,907
Total non-recurring assets at fair value	722,891	767,082	786,849
Level 1 [Member] | Fair Value Measurements on a Nonrecurring Basis
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Impaired loans carried at fair value
Other real estate owned
Covered loans
Covered other real estate owned
Total non-recurring assets at fair value
Level 2 [Member] | Fair Value Measurements on a Nonrecurring Basis
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Impaired loans carried at fair value	50,437	70,296	58,648
Total non-recurring assets at fair value	50,437	70,296	58,648
Level 3 [Member] | Fair Value Measurements on a Nonrecurring Basis
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Other real estate owned	37,325	46,680	50,866
Covered loans	546,234	571,489	595,428
Covered other real estate owned	88,895	78,617	81,907
Total non-recurring assets at fair value	$ 672,454	$ 696,786	$ 728,201