Derivative Financial Instruments Offsetting Derivative Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Offsetting Assets [Line Items]
Derivative asset, fair value	$ 193,897	$ 61,688
Derivative, Collateral, Obligation to Return Securities	403	13,085
Derivative, Collateral, Obligation to Return Cash	0	(23,270)
Net Amount	193,494	25,333
Derivative liability, gross liability	105,044	47,237
Derivative liability, Collateral, Right to Reclaim Securities	(403)	(22,916)
Derivative liability, Collateral, Right to Reclaim Cash	(104,523)	(22,786)
Derivative liability, Net Amount	118	1,535
Interest Rate Swap [Member]
Offsetting Assets [Line Items]
Derivative asset, fair value	193,701	61,401
Derivative, Collateral, Obligation to Return Securities	207	12,955
Derivative, Collateral, Obligation to Return Cash	0	(23,270)
Net Amount	193,494	25,176
Derivative liability, gross liability	104,730	47,107
Derivative liability, Collateral, Right to Reclaim Securities	(207)	(22,786)
Derivative liability, Collateral, Right to Reclaim Cash	(104,523)	(22,786)
Derivative liability, Net Amount	0	1,535
Foreign Exchange Contract [Member]
Offsetting Assets [Line Items]
Derivative asset, fair value	196	287
Derivative, Collateral, Obligation to Return Securities	196	130
Derivative, Collateral, Obligation to Return Cash	0	0
Net Amount	0	157
Derivative liability, gross liability	314	130
Derivative liability, Collateral, Right to Reclaim Securities	(196)	(130)
Derivative liability, Collateral, Right to Reclaim Cash	0	0
Derivative liability, Net Amount	$ 118	$ 0