Stockholders' Equity and Equity-Based Incentive Plans - Changes in the Number of Shares Outstanding and Treasury Shares Held by the Company (Detail) - shares shares in Millions	3 Months Ended
	Mar. 31, 2020		Mar. 31, 2019		Dec. 31, 2019
Shares Outstanding [Abstract]
Beginning balance	193		181
Common stock issued	0		2
Purchase of common stock	0		(1)
Ending balance	193		182
Shares Held as Treasury Shares [Abstract]
Beginning balance	3		3
Purchase of common stock	0		1
Retirement of common stock	0		(1)
Ending balance	3		3
Common stock, shares issued	196	[1]	184	[1]	196

[1] ^{Amounts in this table may not sum due to rounding.}