Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating lease right of use asset	$ 370	$ 573
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssets	us-gaap:OtherAssets
Operating lease liability	$ 501	$ 694
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilities	us-gaap:OtherLiabilities
Total lease expense	$ 110	$ 146
Operating lease expense	84	121
Variable lease expense	22	19
Short term lease expense	4	6
Lease expense			$ 120
Lease liability cash payments	86	117
Operating lease right of use assets obtained in exchange for lease obligations	40	54
Maturities of Lease Liabilities [Abstract]
2021	89
2022	80
2023	72
2024	59
2025	49
Thereafter	317
Total	666
Less: discount	165
Total lease liabilities	$ 501	$ 694
Weighted Average Remaining Lease Term and Discount Rate [Abstract]
Weighted average remaining lease term	9 years 8 months 12 days
Weighted average discount rate	3.50%