Long-term Equity-based Compensation - Option and SAR Activity (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares Subject to Options at Beginning of Year	2,543,673
Weighted Average Exercise Price Per Share at Beginning of Year	$ 41.37
Grants in Period	289,000
Grants in Period, Weighted Average Exercise Price	$ 36.59
Exercises in Period	(46,125)
Exercises in Period, Weighted Average Exercise Price	$ 29.04
Forfeitures and Expirations in Period	(520,837)
Forfeitures and Expirations in Period, Weighted Average Exercise Price	$ 46.94
Shares Subject to Options at End of Year	2,265,711	2,543,673
Weighted Average Exercise Price Per Share at End of Year	$ 39.74	$ 41.37
Outstanding at End of Year, Weighted Average Remaining Contractual Term	3 years 9 months 18 days
Outstanding at End of Year, Intrinsic Value	$ 4.3
Vested and Expected to Vest, Outstanding at End of Year	2,242,297
Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price	$ 39.80
Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term	3 years 9 months 18 days
Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	4.2
Vested and Expected to Vest, Exercisable at End of Year	1,944,207
Vested and Expected to Vest, Exercisable at End of Year, Weighted Average Exercise Price	$ 40.59
Vested and Expected to Vest, Exercisable at End of Year, Weighted Average Remaining Contractual Term	3 years
Vested and Expected to Vest, Exercisable at End of Year, Aggregate Intrinsic Value	3.7
Weighted-average grant-date fair values (per share)	$ 10.49	$ 10.20	$ 9.40
Total intrinsic value	0.4	4.1	3.0
Cash received from exercises of Tandem Awards	0.5	1.7	1.3
Tax benefit realized for tax deductions from exercises of Tandem Awards	$ 0.1	$ 1.4	$ 1.0