Leases - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 214,000,000
Operating lease commitments, not yet commenced	49,000,000
Financing lease commitments	0
Operating lease commitments	1,105,000,000
Lease liabilities, noncurrent	$ 778,000,000
Weighted average remaining lease term for operating lease	7 years
Weighted average operating discount rate used to determine the operating lease	4.00%
Operating cash flow payments	$ 210,000,000
Operating lease, right-of-use asset	298,000,000
Gain (loss) offset by terminations	$ (68,000,000)
Rent expense		$ 250,000,000	$ 238,000,000
Maximum
Lessee, Lease, Description [Line Items]
Operating lease commitments term, not yet commenced	10 years