Severance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019
Restructuring and Related Activities [Abstract]
Operating lease obligation			$ 110
Severance
Restructuring reserve [Roll Forward]
Balance at the beginning of the period	$ 89	$ 87
Accrued to expense	151	89
Payments, net	(137)	(87)
Balance at the end of the period	$ 103	$ 89