v3.20.1

Basis of Presentation and Summary of Significant Accounting Policies - Components of Restricted Cash (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Accounting Policies [Line Items]
Current	$ 260	$ 299
Non-current	46	46
Total	306	345
Debt service
Accounting Policies [Line Items]
Current	53	58
Non-current	7	8
Total	60	66
Construction major maintenance
Accounting Policies [Line Items]
Current	37	28
Non-current	6	6
Total	43	34
Security project insurance
Accounting Policies [Line Items]
Current	166	209
Non-current	31	31
Total	197	240
Other
Accounting Policies [Line Items]
Current	4	4
Non-current	2	1
Total	$ 6	$ 5

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