Supplementary Balance Sheet Information (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Prepaid expenses	$ 32	$ 27
Other receivable	26	22
Spare parts	23	20
Other	36	36
Total prepaid expenses and other current assets	117	105
Operating expenses, payroll and related expenses	137	139
Deferred revenue	10	12
Accrued liabilities to client communities	26	16
Interest payable	46	27
Dividends payable	15	38
Insurance premium financing	28	24
Other	41	36
Total accrued expenses and other current liabilities	$ 303	$ 292