Short and Long-Term Funding (Components of Short-term and Long-term Funding) (Details) - USD ($) $ in Thousands		Mar. 31, 2016	Dec. 31, 2015
Short-term Funding [Abstract]
Federal funds purchased		$ 74,985	$ 47,870
Securities sold under agreements to repurchase		508,262	383,568
Federal funds purchased and securities sold under agreements to repurchase		583,247	431,438
FHLB advances		770,000	335,000
Commercial paper		64,161	67,978
Other short-term funding		834,161	402,978
Total short-term funding		1,417,408	834,416
Long-term Funding
FHLB advances		2,365,216	1,750,225
Senior notes, at par		250,000	680,000
Subordinated notes, at par		250,000	250,000
Other long-term funding and capitalized costs (1)		(3,900)	(4,061)
Total long-term funding	[1]	2,861,316	2,676,164
Total short and long-term funding		$ 4,278,724	$ 3,510,580

[1] During the first quarter of 2016, the Corporation adopted a new accounting standard related to simplifying the presentation of debt issuance costs. Under this new accounting standard, debt issuance costs are still capitalized; however, they are reflected on the balance sheet with the related debt issued rather than within other assets. All prior periods have been restated to reflect this change in presentation. See Note 3 for additional information on this new accounting standard.