SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF PARENT - BALANCE SHEETS (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
ASSETS
Cash and cash equivalents	$ 108	$ 102
Due from affiliates	32	37
Income taxes receivable	112	60
Other current assets	324	249
Total current assets	3,339	3,645
Due from affiliates	742	644
Deferred income taxes	155	141
Other long-term assets	732	962
Total assets	65,665	60,638	$ 50,454
Liabilities and shareholders’ equity:
Current portion of long-term debt	1,526	1,644
Due to affiliates	5	10
Other current liabilities	866	935
Total current liabilities	9,150	7,523
Long-term debt	20,785	20,903
Due to affiliates	195	37
Commitments and contingencies (Note 4)
Total shareholders’ equity	19,929	17,138
Total liabilities and equity	65,665	60,638
Parent Company [Member]
ASSETS
Cash and cash equivalents	6	14	$ 104	$ 12
Due from affiliates	98	93
Income taxes receivable	0	397
Other current assets	34	9
Total current assets	138	513
Investments in subsidiaries	32,604	28,778
Due from affiliates	3	3
Deferred income taxes	1,766	1,554
Other long-term assets	682	572
Total assets	35,193	31,420
Liabilities and shareholders’ equity:
Current portion of long-term debt	1,399	1,498
Due to affiliates	369	287
Income taxes payable, net	274	0
Other current liabilities	561	527
Total current liabilities	2,603	2,312
Long-term debt	8,856	9,647
Due to affiliates	3,138	1,812
Other long-term liabilities	667	511
Commitments and contingencies (Note 4)
Total shareholders’ equity	19,929	17,138
Total liabilities and equity	$ 35,193	$ 31,420