Share-Based Compensation Narrative (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	1 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant under Incentive Plans		25,000
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	12,000
Purchase price percent	90.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term (in years) that awards will be granted		10 years
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of stock options exercised			$ 15	$ 13
Employee Stock Option [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		1 year
Employee Stock Option [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		4 years
Restricted Stock and Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value		$ 6.20	$ 11.94	$ 18.98
Total fair value of awards vested during the period		$ 38	$ 37	$ 52
Unrecognized compensation expense		$ 83
Unrecognized compensation expense, recognition period		2 years
Restricted Stock and Restricted Stock Units (RSUs) [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		2 years
Restricted Stock and Restricted Stock Units (RSUs) [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		5 years
Performance units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
Award vesting		200.00%
Weighted-average grant date fair value		$ 5.11	$ 10.45	$ 14.31
Total fair value of awards vested during the period				$ 11
Unrecognized compensation expense		$ 7
Unrecognized compensation expense, recognition period		2 years
Risk-free interest rate		0.80%
Volatility rate		68.00%
Dividend yield		0.00%
Shares issued for share-based compensation awards (in shares)				541