Debt - Two Thousand Fifteen Credit Facility - Additional Information (Details) - USD ($)		3 Months Ended			9 Months Ended
		Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	May 05, 2020	Dec. 31, 2019	May 12, 2017	Jun. 30, 2015
Debt Instrument [Line Items]
Total interest expense and commitments fees		$ 13,000,000		$ 2,000,000	$ 22,000,000	$ 5,000,000
Unpaid interest and commitment fees	[1]	9,000,000			9,000,000
Second Amendment
Debt Instrument [Line Items]
Minimum liquidity required							$ 150,000,000
2015 Credit Facility
Debt Instrument [Line Items]
Total interest expense and commitments fees		2,000,000		$ 0	9,000,000	$ 1,000,000
2015 Credit Facility | Accrued Expenses and Other Current Liabilities
Debt Instrument [Line Items]
Unpaid interest and commitment fees		1,000,000			$ 1,000,000			$ 0
2015 Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility, expiration period					5 years
Outstanding borrowings		0			$ 0			$ 0
Amount borrowed			$ 700,000,000
Line Of Credit Facility Unused Capacity Commitment Fee Percentage					0.50%
Lender fees and debt financing costs capitalized		4,000,000			$ 4,000,000
2015 Credit Facility | Revolving Credit Facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate					2.25%
Floor Interest Rate					1.00%
2015 Credit Facility | Letter of Credit
Debt Instrument [Line Items]
Borrowing capacity under Credit Facility		15,000,000			$ 15,000,000
Letters of credit outstanding amount		3,000,000			3,000,000
2015 Credit Facility | Borrowings On Same Day Notice
Debt Instrument [Line Items]
Borrowing capacity under Credit Facility		$ 40,000,000			$ 40,000,000
2015 Credit Facility | First Amendment | Revolving Credit Facility
Debt Instrument [Line Items]
Borrowing capacity under Credit Facility									$ 1,200,000,000	$ 1,000,000,000.0
Credit facility, maturity date					Jun. 26, 2020
Credit facility, extended maturity date					May 12, 2022
Credit Facility, description					On May 12, 2017, the 2015 Credit Facility was amended to, among other things, (i) increase the aggregate amount of revolving loan commitments available from $1.0 billion to $1.2 billion; and (ii) extend the maturity date of the 2015 Credit Facility from June 26, 2020 to May 12, 2022 (the “First Amendment”).
2015 Credit Facility | Second Amendment | Revolving Credit Facility
Debt Instrument [Line Items]
Borrowing capacity under Credit Facility							$ 1,000,000,000.0
Credit Facility, description					On May 5, 2020, we amended our 2015 Credit Facility (“Second Amendment”) to, among other things, suspend the leverage ratio covenant on this facility beginning in the second quarter of 2020 and ending prior to September 30, 2021 (or such earlier date as elected by the Company), and replacing it with a minimum liquidity covenant, or the Leverage Covenant Holiday, that requires us to maintain $150 million of unrestricted cash, cash equivalents and short-term investments less deferred merchant payables plus available revolver capacity, which will apply only during the Leverage Covenant Holiday, provide collateral to secure the obligations under the agreement, as well as downsizing its capacity to $1.0 billion from $1.2 billion

[1] Amount relates primarily to accrued interest on our Senior Notes, and to a lesser extent commitment fees on the daily unused portion of our 2015 Credit Facility. Refer to “Note 8: Debt” for additional information.