Accumulated Other Comprehensive Income (Loss) (Components of Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Before-Tax
Net change	$ 105,330	$ 23,091	$ (84,844)	$ 60,289
Tax Effect
Net change	(29,979)	(6,838)	25,830	(18,747)
Net-of-Tax
Other comprehensive income (loss)	75,351	16,253	(59,014)	41,542
AFS Debt Securities
Before-Tax
Net unrealized gains (losses) arising during the period	104,283	34,970	(84,993)	75,463
Net realized losses (gains) reclassified into net income	(632)	(9,640)	(824)	(11,169)
Net change	103,651	25,330	(85,817)	64,294
Tax Effect
Net unrealized gains (losses) arising during the period	(30,789)	(10,364)	25,174	(22,327)
Net realized losses (gains) reclassified into net income	187	2,850	244	3,302
Net change	(30,602)	(7,514)	25,418	(19,025)
Net-of-Tax
Net unrealized gains (losses) arising during the period	73,494	24,606	(59,819)	53,136
Net realized losses (gains) reclassified into net income	(445)	(6,790)	(580)	(7,867)
Other comprehensive income (loss)	73,049	17,816	(60,399)	45,269
Cash Flow Hedges
Before-Tax
Net unrealized gains (losses) arising during the period	(106)	(1,483)	320	(1,483)
Net realized losses (gains) reclassified into net income	201	(377)	378	(377)
Net change	95	(1,860)	698	(1,860)
Tax Effect
Net unrealized gains (losses) arising during the period	30	420	(91)	420
Net realized losses (gains) reclassified into net income	(57)	107	(107)	107
Net change	(27)	527	(198)	527
Net-of-Tax
Net unrealized gains (losses) arising during the period	(76)	(1,063)	229	(1,063)
Net realized losses (gains) reclassified into net income	144	(270)	271	(270)
Other comprehensive income (loss)	68	(1,333)	500	(1,333)
Foreign Currency Translation Adjustments, Net of Hedges
Before-Tax
Net unrealized gains (losses) arising during the period	1,584	(379)	275	(2,145)
Net change	1,584	(379)	275	(2,145)
Tax Effect
Net unrealized gains (losses) arising during the period	650	149	610	(249)
Net change	650	149	610	(249)
Net-of-Tax
Net unrealized gains (losses) arising during the period	2,234	(230)	885	(2,394)
Net realized losses (gains) reclassified into net income	0	0	0	0
Other comprehensive income (loss)	$ 2,234	$ (230)	$ 885	$ (2,394)