Leases - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating lease, right-of-use asset	$ 1,000
Operating lease, liability	1,115
Operating lease, liability, noncurrent	841
New ROU operating lease assets and liabilities entered into	$ 193
Weighted average remaining lease term	8 years 7 months 6 days
Weighted average discount rate	2.80%
Operating lease cost	$ 223	$ 239
Operating lease cost			$ 247
Cash payments	$ 210
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent