Leases - Schedule of Components of Leases (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Current portion of lease liabilities:
Financing	$ 28	$ 30
Total	110	114
Long-term portion of lease liability:
Financing	236	250
Total	612	674
Other Current Liabilities [Member]
Current portion of lease liabilities:
Operating	82	84
Other Noncurrent Liabilities [Member]
Long-term portion of lease liability:
Operating	$ 376	$ 424