Accumulated Other Comprehensive Income (Loss) (Components of Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Before-Tax
Net change	$ (190,174)	$ 37,198
Tax Effect
Net change	55,809	(11,909)
Net-of-Tax
Other comprehensive (loss) income	(134,365)	25,289
AFS Debt Securities
Before-Tax
Net unrealized (losses) gains arising during the period	(189,276)	40,493
Net realized (gains) losses reclassified into net income	(192)	(1,529)
Net change	(189,468)	38,964
Tax Effect
Net unrealized gains arising during the period	55,963	(11,963)
Net realized (gains) losses reclassified into net income	57	452
Net change	56,020	(11,511)
Net-of-Tax
Net unrealized gains (losses) arising during the period	(133,313)	28,530
Net realized (gains) losses reclassified into net income	(135)	(1,077)
Other comprehensive (loss) income	(133,448)	27,453
Cash Flow Hedges
Before-Tax
Net unrealized (losses) gains arising during the period	426	0
Net realized (gains) losses reclassified into net income	177	0
Net change	603	0
Tax Effect
Net unrealized gains arising during the period	(121)	0
Net realized (gains) losses reclassified into net income	(50)	0
Net change	(171)	0
Net-of-Tax
Net unrealized gains (losses) arising during the period	305	0
Net realized (gains) losses reclassified into net income	127	0
Other comprehensive (loss) income	432	0
Foreign Currency Translation Adjustments, Net of Hedges
Before-Tax
Net unrealized (losses) gains arising during the period	(1,309)	(1,766)
Net change	(1,309)	(1,766)
Tax Effect
Net unrealized gains arising during the period	(40)	(398)
Net change	(40)	(398)
Net-of-Tax
Net unrealized gains (losses) arising during the period	(1,349)	(2,164)
Net realized (gains) losses reclassified into net income	0	0
Other comprehensive (loss) income	(1,349)	(2,164)
AOCI, Net of Tax
Net-of-Tax
Net unrealized gains (losses) arising during the period	(134,357)	26,366
Net realized (gains) losses reclassified into net income	(8)	(1,077)
Other comprehensive (loss) income	$ (134,365)	$ 25,289

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