Concentration of Risk - Regional Concentration Based on Net Book Value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Concentration Risk [Line Items]
Net Book Value	$ 22,899,004	$ 20,380,350
Net Assets, Geographic Area | Geographic Region
Concentration Risk [Line Items]
Net Book Value	$ 22,899,004	$ 20,380,350
% of Total	100.00%	100.00%
Net Assets, Geographic Area | Geographic Region | Europe
Concentration Risk [Line Items]
Net Book Value	$ 7,439,993	$ 6,413,557
% of Total	32.50%	31.40%
Net Assets, Geographic Area | Geographic Region | Asia (excluding China)
Concentration Risk [Line Items]
Net Book Value	$ 5,952,981	$ 5,513,498
% of Total	26.00%	27.10%
Net Assets, Geographic Area | Geographic Region | China
Concentration Risk [Line Items]
Net Book Value	$ 2,934,224	$ 2,766,543
% of Total	12.80%	13.50%
Net Assets, Geographic Area | Geographic Region | The Middle East and Africa
Concentration Risk [Line Items]
Net Book Value	$ 2,447,919	$ 2,356,418
% of Total	10.70%	11.60%
Net Assets, Geographic Area | Geographic Region | U.S. and Canada
Concentration Risk [Line Items]
Net Book Value	$ 1,638,450	$ 1,298,974
% of Total	7.20%	6.40%
Net Assets, Geographic Area | Geographic Region | Central America, South America and Mexico
Concentration Risk [Line Items]
Net Book Value	$ 1,566,133	$ 1,074,792
% of Total	6.80%	5.30%
Net Assets, Geographic Area | Geographic Region | Pacific, Australia, and New Zealand
Concentration Risk [Line Items]
Net Book Value	$ 919,304	$ 956,568
% of Total	4.00%	4.70%