Accumulated Other Comprehensive Income (Loss) (Components of AOCI) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 5,269,175	$ 5,017,617	$ 4,423,974
Other comprehensive (loss) income	(134,706)	62,733	39,766
Ending balance	5,837,218	5,269,175	5,017,617
AFS Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	52,247	(2,419)	(45,821)
Net unrealized gains (losses) arising during the period	(136,846)	63,329	46,170
Amount reclassified from AOCI	(1,104)	(8,663)	(2,768)
Other comprehensive (loss) income	(137,950)	54,666	43,402
Ending balance	(85,703)	52,247	(2,419)
Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(1,230)	0	0
Net unrealized gains (losses) arising during the period	866	(1,149)	0
Amount reclassified from AOCI	621	(81)	0
Other comprehensive (loss) income	1,487	(1,230)	0
Ending balance	257	(1,230)	0
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(6,692)	(15,989)	(12,353)
Net unrealized gains (losses) arising during the period	1,757	9,297	(3,636)
Amount reclassified from AOCI	0	0	0
Other comprehensive (loss) income	1,757	9,297	(3,636)
Ending balance	(4,935)	(6,692)	(15,989)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	44,325	(18,408)	(58,174)
Net unrealized gains (losses) arising during the period	(134,223)	71,477	42,534
Amount reclassified from AOCI	(483)	(8,744)	(2,768)
Other comprehensive (loss) income	(134,706)	62,733	39,766
Ending balance	$ (90,381)	$ 44,325	$ (18,408)