Stock-Based Compensation (Details Textual) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Oct. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 18	$ 15	$ 18
Amount of cash received from the exercise of stock options	24
Tax benefit from the exercise of stock options	$ 9
Shares awarded	463
Shares outstanding	2,126	2,561
Non-vested options outstanding	1,000	1,000	1,000
Weighted average grant date fair value	$ 37.10	$ 35.65	$ 32.45
Aggregate intrinsic value of outstanding stock options	$ 34
Aggregate intrinsic value of exercisable stock options	22
Total intrinsic value of options exercised	12	$ 9	$ 10
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unamortized compensation expense	$ 5
Weighted average period	2 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unamortized compensation expense	$ 16
Weighted average period	1 year 8 months 12 days
Shares awarded	314
Performance Based Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unamortized compensation expense	$ 8
Weighted average period	1 year 10 months 24 days
Requisite service periods	3 years
Target payout percentage	100.00%
2011 Omnibus Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares initially available for awards				18,000
Shares available for future grant	8,000