Stock Based Awards and Other Equity Instruments - Summary of MSUs Activity (Details) - MSUs $ / shares in Units, shares in Thousands, $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($) $ / shares shares
MSUs outstanding
Unvested outstanding, Beginning balance | shares	284
Unvested MSUs, Granted | shares	78	[1]
Unvested outstanding, Ending balance | shares	362
Weighted Average Grant-Date Fair Value Per Share
Unvested outstanding, Weighted Average Grant-Date Fair Value Per Share, Beginning balance | $ / shares	$ 37.41
Weighted Average Grant-Date Fair Value Per Share, Granted | $ / shares	57.62	[1]
Unvested outstanding, Weighted Average Grant-Date Fair Value Per Share, Ending balance | $ / shares	$ 41.76
Aggregate Intrinsic Value
Unvested MSUs outstanding, Aggregate Intrinsic Value | $	$ 17

[1] MSUs provide for vesting based upon the Company’s total shareholder return, or TSR, performance over the period commencing January 1, 2019 through December 31, 2021 relative to the TSR performance of the Nasdaq Composite Total Return Index. Based upon actual attainment relative to the target performance metric, the grantee has the ability to receive up to 200% of the target number of MSUs originally granted, or to be issued none at all.