Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Numerator:
Net income attributable to stockholders		$ 96	$ 150
Net income attributable to stockholders net of earnings allocated to participating securities		$ 96	$ 150
Denominator:
Weighted average shares outstanding – basic		201	211
Unvested restricted shares		1	1
Weighted average shares outstanding – diluted		202	212
Basic EPS	[1]	$ 0.48	$ 0.71
Diluted EPS	[1]	$ 0.48	$ 0.71

[1] Per share amounts are calculated based on unrounded numbers.