Stock Based Compensation (Details 4) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
General information on stock-based compensation
Stock based compensation expense	$ 51.8	$ 33.5	$ 39.5
Performance Share Awards
Stock-Based Compensation arrangements
Number of types of performance awards granted to employees	3
Performance period	3 years
General information on stock-based compensation
Stock based compensation expense	30.9	24.6	28.5
Performance Share Awards | Low end of range
Stock-Based Compensation arrangements
Annual forfeiture rate assumption (as a percent)	0.00%
Performance Share Awards | High end of range
Stock-Based Compensation arrangements
Annual forfeiture rate assumption (as a percent)	7.00%
Performance shares based on performance conditions
Stock-Based Compensation arrangements
Number of types of performance awards granted to employees	2
Performance shares based on performance conditions | High end of range
Stock-Based Compensation arrangements
Right to receive shares (as a percent)	100.00%
Employee Performance Share Awards
Stock-Based Compensation arrangements
Vesting rights	An employee will earn one-third of the award for each of the three performance metrics that the Company meets
Number of criteria considered for awarding performance shares	3
Number of years over which performance criteria is to be met	3 years
Shares or units
Outstanding at beginning of year (in shares)	1,919,640	2,627,900	2,497,040
Granted (in shares)	379,540	567,360	837,460
Issued and Fully Vested (in shares)	(610,960)	(1,189,920)	(575,200)
Forfeited (in shares)	(30,240)	(85,700)	(131,400)
Outstanding at the end of the period (in shares)	1,657,980	1,919,640	2,627,900
Weighted-Average Grant Date Fair Value per Share
Outstanding at the beginning of the period (in dollars per share)	$ 12.27	$ 8.12	$ 8.35
Granted (in dollars per share)	$ 26.62	$ 17.59	$ 10.19
Issued and Fully Vested (in dollars per share)	$ 10.13	$ 5.66	$ 12.12
Forfeited (in dollars per share)	$ 17.06	$ 12.11	$ 8.10
Outstanding at the end of the period (in dollars per share)	$ 16.25	$ 12.27	$ 8.12
Hybrid Performance Share Awards
Stock-Based Compensation arrangements
Vesting rights	The 2013 awards vest 25% on each of the first and second anniversary dates and 50% on the third anniversary and the 2012 and 2011 awards vest one-third on each anniversary date
Performance period	3 years
Minimum operating cash flow for the year preceding the performance period	100
Shares or units
Outstanding at beginning of year (in shares)	592,162	759,328	763,576
Granted (in shares)	169,980	234,922	370,784
Issued and Fully Vested (in shares)	(311,930)	(402,088)	(375,032)
Outstanding at the end of the period (in shares)	450,212	592,162	759,328
Weighted-Average Grant Date Fair Value per Share
Outstanding at the beginning of the period (in dollars per share)	$ 13.11	$ 9.16	$ 8.25
Granted (in dollars per share)	$ 26.62	$ 17.59	$ 10.19
Issued and Fully Vested (in dollars per share)	$ 12.03	$ 8.27	$ 8.32
Outstanding at the end of the period (in dollars per share)	$ 18.96	$ 13.11	$ 9.16
Performance shares based on market conditions
Stock-Based Compensation arrangements
Number of types of performance awards granted to employees	1
TSR Performance Share Awards
Stock-Based Compensation arrangements
Performance period	3 years
Shares or units
Outstanding at beginning of year (in shares)	605,706	1,495,904	1,415,168
Granted (in shares)	254,980	234,922	370,784
Issued and Fully Vested (in shares)		(1,125,120)	(290,048)
Outstanding at the end of the period (in shares)	860,686	605,706	1,495,904
Weighted-Average Grant Date Fair Value per Share
Outstanding at the beginning of the period (in dollars per share)	$ 10.27	$ 6.07	$ 6.50
Granted (in dollars per share)	$ 23.06	$ 14.16	$ 7.81
Issued and Fully Vested (in dollars per share)		$ 5.49	$ 10.38
Outstanding at the end of the period (in dollars per share)	$ 14.06	$ 10.27	$ 6.07
TSR Performance Share Awards | Equity Component
Assumptions
Fair value per performance share award at the end of the period	$ 23.06	$ 14.16	$ 7.81
Stock price volatility (as a percent)	43.80%	46.70%	62.00%
Risk free rate of return (as a percent)	0.40%	0.40%	1.30%
Expected dividend yield (as a percent)	0.20%	0.20%	0.20%
TSR Performance Share Awards | Liability Component
General information on stock-based compensation
Non-current portion of the liability , included in Other Liabilities	7.8	7.6
Current portion of the liability, included in Other Liabilities	14.3	0
Cash payment		$ 18.4
Assumptions
Stock Price Volatility, low end of range (as a percent)	30.20%	41.10%	41.90%
Stock Price Volatility, high end of range (as a percent)	35.90%	45.70%	42.70%
Risk free rate of return, low end of range (as a percent)	0.10%	0.20%	0.10%
Risk free rate of return, high end of range (as a percent)	0.40%	0.30%	0.30%
Expected dividend yield (as a percent)	0.20%	0.20%	0.20%
TSR Performance Share Awards | Low end of range
Stock-Based Compensation arrangements
Number of other companies in the Company's peer group	15
TSR Performance Share Awards | Low end of range | Liability Component
Assumptions
Fair value per performance share award at the end of the period	$ 23.96	$ 19.11	$ 12.82
TSR Performance Share Awards | High end of range
Stock-Based Compensation arrangements
Right to receive shares (as a percent)	100.00%
Number of other companies in the Company's peer group	16
Weighted-Average Grant Date Fair Value per Share
Right to receive additional shares (as a percent)	100.00%
TSR Performance Share Awards | High end of range | Liability Component
Assumptions
Fair value per performance share award at the end of the period	$ 38.61	$ 24.76	$ 17.74