Other Assets (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Other Assets [Abstract]
Cash surrender value of bank owned life insurance	$ 271,036,000	$ 262,587,000
Accrued interest receivable	70,138,000	81,992,000
Accounts receivable	21,371,000	24,130,000
FHLB and FRB Stock	66,168,000	78,100,000
Private equity investments	31,876,000	22,015,000
Prepaid FDIC deposit insurance assessments	34,401,000	76,574,000
Other prepaid expenses	28,576,000	22,454,000
Net current income tax receivable	813,000	3,704,000
Net deferred income taxes	806,406,000	2,138,000
Derivative asset positions	64,662,000	84,923,000
Other properties held for sale	9,871,000	17,246,000
Miscellaneous other assets	61,466,000	70,961,000
Total other assets	660,378,000	744,686,000
Separate account life insurance	$ 30,900,000	$ 30,700,000