Accumulated Other Comprehensive Income (Loss) (Components of Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Before-Tax
Net change	$ 23,091	$ 40,095	$ 60,289	$ 72,652
Tax Effect
Net change	(6,838)	(17,084)	(18,747)	(24,450)
Net-of-Tax
Other comprehensive income	16,253	23,011	41,542	48,202
AFS Debt Securities
Before-Tax
Net unrealized gains arising during the period	34,970	44,531	75,463	75,469
Net realized (gains) reclassified into net income	(9,640)	(1,447)	(11,169)	(3,008)
Net change	25,330	43,084	64,294	72,461
Tax Effect
Net unrealized gains (losses) arising during the period	(10,364)	(14,485)	(22,327)	(22,312)
Net realized (gains) reclassified into net income	2,850	428	3,302	889
Net change	(7,514)	(14,057)	(19,025)	(21,423)
Net-of-Tax
Net unrealized gains (losses) arising during the period	24,606	30,046	53,136	53,157
Net realized (gains) reclassified into net income	(6,790)	(1,019)	(7,867)	(2,119)
Other comprehensive income	17,816	29,027	45,269	51,038
Cash Flow Hedges
Before-Tax
Net unrealized gains arising during the period	(1,483)	0	(1,483)	0
Net realized (gains) reclassified into net income	(377)	0	(377)	0
Net change	(1,860)	0	(1,860)	0
Tax Effect
Net unrealized gains (losses) arising during the period	420	0	420	0
Net realized (gains) reclassified into net income	107	0	107	0
Net change	527	0	527	0
Net-of-Tax
Net unrealized gains (losses) arising during the period	(1,063)	0	(1,063)	0
Net realized (gains) reclassified into net income	(270)	0	(270)	0
Other comprehensive income	(1,333)	0	(1,333)	0
Foreign Currency Translation Adjustments, Net of Hedges
Before-Tax
Net unrealized gains arising during the period	(379)	(2,989)	(2,145)	191
Net change	(379)	(2,989)	(2,145)	191
Tax Effect
Net unrealized gains (losses) arising during the period	149	(3,027)	(249)	(3,027)
Net change	149	(3,027)	(249)	(3,027)
Net-of-Tax
Net unrealized gains (losses) arising during the period	(230)	(6,016)	(2,394)	(2,836)
Net realized (gains) reclassified into net income	0	0	0	0
Other comprehensive income	$ (230)	$ (6,016)	$ (2,394)	$ (2,836)