Accumulated Other Comprehensive Income (Loss) (Components of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 5,837,218	$ 5,269,175
Other comprehensive loss	(304,544)	(134,365)
Ending balance	5,703,456	5,285,027
Net changes in unrealized losses on securities transferred from AFS to HTM	113,000
Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(85,703)	52,247
Net unrealized (losses) gains arising during the period	(281,361)	(133,313)
Amounts reclassified from AOCI	1,411	(135)
Other comprehensive loss	(279,950)	(133,448)
Ending balance	(365,653)	(81,201)
Net changes in unrealized losses on securities transferred from AFS to HTM	(2,311)	0
Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	257	(1,230)
Net unrealized (losses) gains arising during the period	(23,227)	305
Amounts reclassified from AOCI	(1,496)	127
Other comprehensive loss	(24,723)	432
Ending balance	(24,466)	(798)
Foreign Currency Translation Adjustments, Net of Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(4,935)	(6,692)
Net unrealized (losses) gains arising during the period	129	(1,349)
Amounts reclassified from AOCI	0	0
Other comprehensive loss	129	(1,349)
Ending balance	(4,806)	(8,041)
AOCI, Net of Tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(90,381)	44,325
Net unrealized (losses) gains arising during the period	(304,459)	(134,357)
Amounts reclassified from AOCI	(85)	(8)
Other comprehensive loss	(304,544)	(134,365)
Ending balance	$ (394,925)	$ (90,040)