Net Income Per Share (Tables)

6 Months Ended

Jun. 30, 2017

Earnings Per Share [Abstract]

Reconciliation of earnings attributable to common stockholders, basic and diluted

	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
	(in millions)
Net income (loss) attributable to common stockholders	$	233		$	(268	)	$	191		$	(535	)
Participating share-based earnings	(2		)	—			(2		)	—
Basic and diluted net income (loss) attributable to common stockholders	$	231		$	(268	)	$	189		$	(535	)