Fair Value (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Other noninterest-bearing investments valued under the cost method	$ 59,300,000		$ 59,300,000		$ 74,800,000
Federal Home Loan Bank Stock and Federal Reserve Bank Stock	226,200,000		226,200,000		232,500,000
Percentage of bank issuers are public companies	31.00%
Weighted average assumed loss rate on deferring collateral	53.00%		53.00%
Net gains on sale of OREO properties	(439,000)	(5,509,000)	(492,000)	(13,341,000)
Principal amount of other real estate owned property sold			39,000,000	84,700,000
Highest Quality/Most Over-Collateralized Insurance-Only Tranches Discount Rate [Member]
Derivatives, Fair Value [Line Items]
Valuations for bank and insurance tranches utilized a discount rate range of LIBOR	3.75%
Lowest Credit Quality Tranche Discount Rate [Member]
Derivatives, Fair Value [Line Items]
Valuations for bank and insurance tranches utilized a discount rate range of LIBOR	21.00%
AAA [Member]
Derivatives, Fair Value [Line Items]
Percentage of difference between rated bonds	5.00%
BBB [Member]
Derivatives, Fair Value [Line Items]
Percentage of difference between rated bonds	14.00%
A-Rated Bonds [Member]
Derivatives, Fair Value [Line Items]
Percentage of difference between rated bonds	7.00%
OREO Properties [Member]
Derivatives, Fair Value [Line Items]
Net gains on sale of OREO properties	2,100,000	2,900,000	6,300,000	5,800,000
Impairment of OREO properties	(300,000)	(3,200,000)	(400,000)	(3,900,000)
Minimum [Member] | Highest Quality/Most Over-Collateralized Insurance-Only Tranches Discount Rate [Member]
Derivatives, Fair Value [Line Items]
Valuations for bank and insurance tranches utilized a discount rate range of LIBOR	5.60%
Best [Member]
Derivatives, Fair Value [Line Items]
Percentage of resulting five-year PDs	11.00%		11.00%
Worst [Member]
Derivatives, Fair Value [Line Items]
Percentage of resulting five-year PDs	100.00%		100.00%
First Priority Original AAA-Rated Bonds Discount Rate [Member] | Minimum [Member]
Derivatives, Fair Value [Line Items]
Discount rate range of LIBOR utilized for fair value purposes	5.60%		5.60%
Lower Priority Original AAA-Rated Bonds Discount Rate [Member] | Minimum [Member]
Derivatives, Fair Value [Line Items]
Discount rate range of LIBOR utilized for fair value purposes	5.60%		5.60%
Lower Priority Original AAA-Rated Bonds Discount Rate [Member] | Maximum [Member]
Derivatives, Fair Value [Line Items]
Discount rate range of LIBOR utilized for fair value purposes	6.30%		6.30%
Lower Priority Original AAA-Rated Bonds Discount Rate [Member] | Weighted Average [Member]
Derivatives, Fair Value [Line Items]
Discount rate average of LIBOR utilized for fair value purposes	5.70%		5.70%
Original A-Rated Bonds Discount Rate [Member] | Minimum [Member]
Derivatives, Fair Value [Line Items]
Discount rate range of LIBOR utilized for fair value purposes	5.90%		5.90%
Original A-Rated Bonds Discount Rate [Member] | Maximum [Member]
Derivatives, Fair Value [Line Items]
Discount rate range of LIBOR utilized for fair value purposes	16.20%		16.20%
Original A-Rated Bonds Discount Rate [Member] | Weighted Average [Member]
Derivatives, Fair Value [Line Items]
Discount rate average of LIBOR utilized for fair value purposes	8.70%		8.70%
Original BBB-Rated Bonds Discount Rate [Member] | Minimum [Member]
Derivatives, Fair Value [Line Items]
Discount rate range of LIBOR utilized for fair value purposes	9.20%		9.20%
Original BBB-Rated Bonds Discount Rate [Member] | Maximum [Member]
Derivatives, Fair Value [Line Items]
Discount rate range of LIBOR utilized for fair value purposes	21.00%		21.00%
Original BBB-Rated Bonds Discount Rate [Member] | Weighted Average [Member]
Derivatives, Fair Value [Line Items]
Discount rate average of LIBOR utilized for fair value purposes	16.30%		16.30%
Level 2 [Member]
Derivatives, Fair Value [Line Items]
Fair value of AFS securities	1,805,867,000		1,805,867,000		1,765,214,000
Level 2 [Member] | Available-for-sale Securities [Member]
Derivatives, Fair Value [Line Items]
Fair value of AFS securities	1,800,000,000		1,800,000,000
Level 3 [Member]
Derivatives, Fair Value [Line Items]
Fair value of AFS securities	1,086,214,000		1,086,214,000		1,003,900,000
Level 3 [Member] | Available-for-sale Securities [Member]
Derivatives, Fair Value [Line Items]
Fair value of AFS securities	1,100,000,000		1,100,000,000
Level 3 [Member] | Municipal Securities [Member]
Derivatives, Fair Value [Line Items]
Fair value of AFS securities	53,000,000		53,000,000
Level 3 [Member] | Other (Including ABS CDOs) [Member]
Derivatives, Fair Value [Line Items]
Fair value of AFS securities	3,000,000		3,000,000
Third Party Pricing Service [Member] | Level 2 [Member]
Derivatives, Fair Value [Line Items]
Fair value of AFS securities	1,700,000,000		1,700,000,000
Third Party Pricing Service [Member] | Level 3 [Member]
Derivatives, Fair Value [Line Items]
Fair value of AFS securities	80,000,000		80,000,000
Licensed Internal Third Party [Member] | Level 3 [Member]
Derivatives, Fair Value [Line Items]
Fair value of AFS securities	1,004,000,000		1,004,000,000
Market Corroborative Data [Member] | Level 2 [Member]
Derivatives, Fair Value [Line Items]
Fair value of AFS securities	6,000,000		6,000,000
Market Corroborative Data [Member] | Level 2 [Member] | FAMC Securities [Member]
Derivatives, Fair Value [Line Items]
Fair value of AFS securities	$ 104,000,000		$ 104,000,000