Accrued Expenses and Other Current Liabilities - Details of Accrued Expenses and Other Current Liabilities (Parenthetical) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Accrued Expenses And Other Current Liabilities [Line Items]
Pre-tax restructuring and other related reorganization costs			$ 41	$ 1
Employee Severance and Related Benefits
Accrued Expenses And Other Current Liabilities [Line Items]
Pre-tax restructuring and other related reorganization costs	$ 32	$ 9	$ 41