Fair Value (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Fair Value Level Transfers Among Levels 1, 2, and 3	0	0	0	0
Other noninterest-bearing investments valued under the cost method	$ 48,500,000		$ 48,500,000		$ 53,600,000
Federal Home Loan Bank Stock and Federal Reserve Bank Stock	246,500,000		246,500,000		248,400,000
Net gains on sale of OREO properties	266,000	(1,590,000)	(1,341,000)	(3,567,000)
Principal amount of other real estate owned property sold			24,600,000	38,700,000
Private equity investments prohibited by Volker rule	56,000,000		56,000,000
OREO Properties [Member]
Derivatives, Fair Value [Line Items]
Net gains on sale of OREO properties	1,500,000	2,100,000	2,500,000	6,300,000
Impairment of OREO properties	(300,000)	(300,000)	(500,000)	(400,000)
Level 2 [Member]
Derivatives, Fair Value [Line Items]
Fair value of AFS securities	2,584,743,000		2,584,743,000		2,137,259,000
Level 3 [Member]
Derivatives, Fair Value [Line Items]
Fair value of AFS securities	702,449,000		702,449,000		1,304,877,000
Third Party Pricing Service [Member] | Level 2 [Member]
Derivatives, Fair Value [Line Items]
Fair value of AFS securities	0		0
Third Party Pricing Service [Member] | Level 3 [Member]
Derivatives, Fair Value [Line Items]
Fair value of AFS securities	$ 0		$ 0