Short and Long-Term Funding (Components of Short-term and Long-term Funding) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Short-Term Funding
Federal funds purchased	$ 256,655	$ 109,770
Securities sold under agreements to repurchase	433,044	384,221
Federal funds purchased and securities sold under agreements to repurchase	689,699	493,991
FHLB advances	850,000	500,000
Commercial paper	55,837	74,297
Other short-term funding	905,837	574,297
Total short-term funding	1,595,536	1,068,288
Long-Term Funding
FHLB advances	2,250,243	3,000,260
Senior notes, at par	680,000	680,000
Subordinated notes, at par	250,000	250,000
Other long-term funding and capitalized costs	(509)	(143)
Total long-term funding	3,179,734	3,930,117
Total short and long-term funding	$ 4,775,270	$ 4,998,405