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Share-Based Compensation - Additional Information (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Allocated share-based compensation expense $ 15 $ 8 $ 8
Total tax benefit recognized related to share-based compensation 4 $ 3 $ 3
Unrecognized compensation costs for unvested awards $ 11    
Unrecognized compensation costs, weighted average period for recognition 1 year 10 months 24 days    
Shares of common stock available for future issuance 7,652,477    
Restricted Stock Units (RSUs)      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Achievement percentage 100.00%