Revenue Recognition - Additional Information (Details) - Retained Earnings - USD ($) $ in Millions	Jan. 01, 2019	Jan. 01, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cumulative effect of accounting change	$ 0	$ (8)	[1]
ASU 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cumulative effect of accounting change		$ (8)

[1] Financial information for prior periods has been recast to reflect the retrospective application of the successful efforts method of accounting. See Note 1.