Acquisitions - HPES Merger Defined Benefit Pension Plans (Details) - HPES - Defined Benefit Pension Plans $ in Millions	Apr. 01, 2017 USD ($)
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]
Other assets	$ 558
Accrued expenses and other current liabilities	(13)
Other long-term liabilities	(547)
Net amount recorded	(2)
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Projected benefit obligation	(7,413)
Fair value of plan assets	7,411
Funded status	$ (2)
Defined Benefit Plan, Information about Plan Assets [Abstract]
Percent of plan assets	100.00%
Employer contributions:
2018	$ 39
Benefit payments:
2018	225
2019	151
2020	163
2021	224
2022	180
2023 through 2027	$ 1,132
Equity securities
Defined Benefit Plan, Information about Plan Assets [Abstract]
Percent of plan assets	22.00%
Debt securities
Defined Benefit Plan, Information about Plan Assets [Abstract]
Percent of plan assets	72.00%
Alternatives
Defined Benefit Plan, Information about Plan Assets [Abstract]
Percent of plan assets	5.00%
Cash and other
Defined Benefit Plan, Information about Plan Assets [Abstract]
Percent of plan assets	1.00%