Accumulated Other Comprehensive Income (Loss) (Components of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Jan. 01, 2020	[1]	Jan. 01, 2019	[2]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 5,017,617	$ 4,423,974
Cumulative effect of a change in accounting principle			$ (97,967)		$ 14,668
Net unrealized gains (losses) arising during the period	26,366	26,291
Amounts reclassified from AOCI	(1,077)	(1,100)
Other comprehensive income	25,289	25,191
Ending balance	4,902,985	4,591,930
Available- for-Sale Investment Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(2,419)	(45,821)
Net unrealized gains (losses) arising during the period	28,530	23,111
Amounts reclassified from AOCI	(1,077)	(1,100)
Other comprehensive income	27,453	22,011
Ending balance	25,034	(23,810)
Foreign Currency Translation Adjustments, Net of Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(15,989)	(12,353)
Net unrealized gains (losses) arising during the period	(2,164)	3,180
Amounts reclassified from AOCI	0	0
Other comprehensive income	(2,164)	3,180
Ending balance	(18,153)	(9,173)
AOCI, Net of Tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(18,408)	(58,174)
Other comprehensive income	25,289	25,191
Ending balance	$ 6,881	$ (32,983)

[1] Represents the impact of the adoption of ASU 2016-13, Financial Instruments - Credit Losses (Topic 326) in the first quarter of 2020. Refer to Note 2 — Summary of Significant Accounting Policies to the Consolidated Financial Statements in this Quarterly Report on Form 10-Q (“this Form 10-Q”) for additional information.

[2] Represents the impact of the adoption of Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842) and subsequent related ASUs in the first quarter of 2019.