Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Numerator:
Net income attributable to stockholders		$ 150	$ 2,350
Earnings allocated to participating securities			(2)
Net income attributable to stockholders net of earnings allocated to participating securities		$ 150	$ 2,348
Denominator:
Weighted average shares outstanding - basic		211	202
Unvested restricted shares		1
Net effect of shares issued with respect to E&P Dividend	[1]		11
Weighted average shares outstanding - diluted		212	213
Basic EPS	[2]	$ 0.71	$ 11.63
Diluted EPS	[2]	$ 0.71	$ 11.01

[1] Shares issued in connection with the distribution of our C corporation earnings and profits attributable to the period prior to spin-off (“E&P Dividend”).

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