Short and Long-Term Funding (Components of Short-term and Long-term Funding) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Short-term Funding [Abstract]
Federal funds purchased	$ 221,165	$ 47,870
Securities sold under agreements to repurchase	477,607	383,568
Federal funds purchased and securities sold under agreements to repurchase	698,772	431,438
FHLB advances	450,000	335,000
Commercial paper	91,321	67,978
Other short-term funding	541,321	402,978
Total short-term funding	1,240,093	834,416
Long-term Funding
FHLB advances	2,265,198	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	(3,563)	(4,061)
Total long-term funding	2,761,635	2,676,164
Total short and long-term funding	$ 4,001,728	$ 3,510,580