Share-Based Compensation - Textuals (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of shares reserved for future grant under the LTIP (in shares)	7,000,000
Income tax benefits on share based arrangements	$ 0
Share-based Compensation Arrangement by Share-based Payment Award [lLine Items]
Expense for share-based arrangements	18,000,000	$ 18,000,000	$ 14,000,000
Deferred compensation arrangement adjustment to equity	$ 6,000,000
MSUs
Share-based Compensation Arrangement by Share-based Payment Award [lLine Items]
Vesting period	3 years
Minimum number of performance shares earned (as a percent)	0.00%
Maximum number of performance shares earned (as a percent)	150.00%
Awards vested (in shares)	417,001
Number of shares vested (in shares)	554,624
Unrecognized compensation cost	$ 5,000,000
Weighted average period for recognition of unrecognized compensation cost	1 year 8 months
Granted (in shares)	371,000
Performance shares
Share-based Compensation Arrangement by Share-based Payment Award [lLine Items]
Vesting period	3 years
Minimum number of performance shares earned (as a percent)	0.00%
Maximum number of performance shares earned (as a percent)	200.00%
Awards vested (in shares)	99,238
Number of shares vested (in shares)	0
Unrecognized compensation cost	$ 4,000,000
Weighted average period for recognition of unrecognized compensation cost	1 year 9 months 18 days
Granted (in shares)	113,000
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [lLine Items]
Vesting period	3 years
Awards vested (in shares)	54,000
Unrecognized compensation cost	$ 5,000,000
Weighted average period for recognition of unrecognized compensation cost	2 years 2 months 12 days
Granted (in shares)	133,000
Fair value of RSUs that vested in period	$ 2,000,000	2,000,000	4,000,000
Employee stock option
Share-based Compensation Arrangement by Share-based Payment Award [lLine Items]
Expiration period of stock options	10 years
(Loss) income from discontinued operations
Share-based Compensation Arrangement by Share-based Payment Award [lLine Items]
Expense for share-based arrangements		$ 1,000,000	$ 1,000,000