Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	5,630,000	5,630,000
Compensation Expense
Compensation expense		$ 18
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	2,000,000	2,000,000
Vesting period		3 years
Period after grant date		1 year
Expiration period		10 years
Options granted in period (in shares)		991,101
Grant date fair value (in dollars per share)		$ 4.91
Assumptions Used
Risk-free interest rate		2.05%
Expected option life		6 years
Expected stock volatility		21.55%
Compensation Expense
Outstanding shares (in shares)			2,745,016
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		3 years
Units granted in period (in shares)		261,877
Grant date fair value (in dollars per share)		$ 18.86
Restricted stock and restricted stock units
Compensation Expense
Unvested shares (in shares)			1,457,900
Performance units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units granted in period (in shares)		158,900
Grant date fair value (in dollars per share)		$ 21.17
Performance period		3 years
Maximum target award percentage		200.00%
Assumptions Used
Expected stock volatility		31.80%
Compensation Expense
Unvested shares (in shares)			291,492
Restricted stock units, performance units and stock options
Compensation Expense
Compensation expense	$ 3