Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Provisional tax benefit, amount			$ 555
Tax benefit favorably impacting effective tax rate		$ (83)
Unrecognized tax benefits that would impact effective income tax rate	$ 432	435
Liabilities recorded for interest related to uncertain tax positions	40	21
Current:
Federal and foreign	415	(39)	777
State and local	126	31	130
Total current	541	(8)	907
Deferred:
Federal and foreign	95	408	(736)
State and local	5	94	(37)
Total deferred	100	502	(773)
Income tax expense	$ 641	$ 494	$ 134
Effective income tax rate:
Effective income tax rate reconciliation (as a percent)	21.00%	21.00%	35.00%
State income taxes-net of federal effect (as a percent)	4.10%	6.10%	3.40%
Tax Reform (as a percent)	0.00%	0.00%	(31.00%)
Accounting method changes (as a percent)	0.00%	(3.90%)	0.00%
Other (as a percent)	0.90%	(0.30%)	0.10%
Effective income tax rate (as a percent)	26.00%	22.90%	7.50%
Deferred tax liabilities:
Property, plant and equipment	$ (1,256)	$ (1,026)
Intangibles assets	(280)	(419)
Total deferred tax liabilities	(1,536)	(1,445)
Deferred tax assets:
Payable to affiliate due to post-retirement benefit plan participation	326	297
Other	20	58
Gross deferred tax assets	346	355
Less valuation allowance on deferred tax assets	(8)	(8)
Net deferred tax assets	338	347
Net deferred tax liabilities	$ (1,198)	$ (1,098)