Short and Long-Term Funding (Components of Short-term and Long-term Funding) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Short-term Funding [Abstract]
Federal funds purchased	$ 345,350	$ 208,150
Securities sold under agreements to repurchase	262,319	300,197
Federal funds purchased and securities sold under agreements to repurchase	607,669	508,347
FHLB advances	697,000	482,000
Commercial paper	97,813	101,688
Other short-term funding	794,813	583,688
Total short-term funding	1,402,482	1,092,035
Long-term Funding
FHLB advances	2,765,176	2,265,188
Senior notes, at par	250,000	250,000
Subordinated notes, at par	250,000	250,000
Other long-term funding and capitalized costs	(3,056)	(3,393)
Total long-term funding	3,262,120	2,761,795
Total short and long-term funding	$ 4,664,602	$ 3,853,830