Acquisitions, Investments and Dispositions - Pro Forma Supplemental Information (Details) - USD ($) $ in Millions		12 Months Ended
	Dec. 13, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Combinations [Abstract]
Revenues		$ 12,574	$ 12,337	$ 12,033
Net income		1,343	1,382	1,525
If Acquired January 1, 2017 (a)(b)
Revenue			12,655	12,331
Net income			1,279	$ 1,612
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Interest expense		37	38
Business acquisition, pre-tax gain from interests in projects	$ 131		131
Pro Forma
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Income from equity method investment		33	$ 32
Term Loan
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Short-term borrowings		$ 825
Fixed interest rate		4.64%