Short and Long-Term Funding (Components of Short-term and Long-term Funding) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Short-term Funding [Abstract]
Federal funds purchased	$ 75	$ 19,710
Securities sold under agreements to repurchase	77,953	91,941
Federal funds purchased and securities sold under agreements to repurchase	78,028	111,651
Commercial paper	30,416	45,423
Total short-term funding	108,444	157,074
Long-Term Funding
Corporation subordinated notes, at par, due 2025	250,000	250,000
Other long-term funding and capitalized costs	(3,201)	(4,389)
Total long-term funding	796,799	795,611
Total short and long-term funding, excluding FHLB advances	905,243	952,685
FHLB Advances
Short-term FHLB advances	215,000	900,000
Long-term FHLB advances	2,662,727	2,674,371
Total FHLB advances	2,877,727	3,574,371
Total short and long-term funding, excluding FHLB advances	3,782,970	4,527,056
Corporation senior notes, at par, due 2019
Long-Term Funding
Senior notes	250,000	250,000
Bank senior notes, at par, due 2021
Long-Term Funding
Senior notes	$ 300,000	$ 300,000