Short and Long-term Funding, Composition (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Short-term Debt [Abstract]
Federal funds purchased	$ 19,710	$ 141,950
Securities sold under agreements to repurchase	91,941	182,865
Federal funds purchased and securities sold under agreements to repurchase	111,651	324,815
Commercial paper	45,423	67,467
Total short-term funding	157,074	392,282
Senior notes, at par	550,000	250,000
Subordinated notes, at par	250,000	250,000
Other long-term funding and capitalized costs	(4,389)	(2,718)
Other Long-term Debt	795,611	497,282
Total short and long-term funding, excluding FHLB advances	952,685	889,564
Short-term FHLB advances	900,000	284,000
Long-term FHLB advances	2,674,371	2,900,168
Total FHLB advances	3,574,371	3,184,168
Total short and long-term funding	$ 4,527,056	$ 4,073,732