Debt - Schedule of Interest Expense (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Debt Disclosure [Abstract]
Contractual interest coupon		$ 3	$ 19	$ 10	$ 39
Amortization of debt issuance costs		1	2	3	4
Amortization of debt discounts	[1]		44		88
Total		$ 4	$ 65	$ 13	$ 131

[1] Under the modified retrospective method of adoption of ASU 2020-06, there was neither amortization of debt discounts, nor losses on extinguishment of debt recognized for the three and six months ended June 30, 2021. Refer to discussion above for further details.