Stock-based Compensation (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended																				12 Months Ended			12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Performance-based Restricted Stock Units [Member]	Dec. 31, 2012 Performance-based Restricted Stock Units [Member]	Dec. 31, 2011 Performance-based Restricted Stock Units [Member]	Dec. 31, 2013 Stock Options [Member]	Dec. 31, 2012 Stock Options [Member]	Dec. 31, 2011 Stock Options [Member]	Dec. 31, 2013 Restricted Stock Units And Deferred Stock Units [Member]	Dec. 31, 2012 Restricted Stock Units And Deferred Stock Units [Member]	Dec. 31, 2011 Restricted Stock Units And Deferred Stock Units [Member]	Dec. 31, 2013 Restricted Stock Units [Member]	Dec. 31, 2013 Deferred Stock Units (DSU) [Member]	Dec. 31, 2013 Unvested Stock Options [Member]	Dec. 31, 2012 Unvested Stock Options [Member]	Dec. 31, 2002 Option Plan 2002 [Member] Stock Options [Member]	Dec. 31, 2011 Option Plan 2002 [Member] Stock Options [Member]	Dec. 31, 2008 Option Plan 2002 [Member] Stock Options [Member]	Dec. 31, 2008 Amended And Restated 2003 Equity Incentive Plan [Member] Stock Options [Member]	Dec. 31, 2013 Stock Option Plans 2002, 2003 and 2013 [Member]	Dec. 31, 2012 Stock Option Plans 2002, 2003 and 2013 [Member]	Dec. 31, 2009 Long Term Incentive Plan 2013 [Member]	Dec. 31, 2013 Treasury Stock [Member]	Dec. 31, 2012 Treasury Stock [Member]	Dec. 31, 2011 Treasury Stock [Member]	Dec. 31, 2013 Treasury Stock [Member] Performance-based Restricted Stock Units [Member]	Dec. 31, 2013 Minimum [Member] Performance-based Restricted Stock Units [Member]	Dec. 31, 2013 Maximum [Member] Performance-based Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of stock units released																											282.00%
Award Requisite Service Period																	4 years
Share-based Payment Award, Expiration period																	10 years from the grant date
Share-based Payment Award, Expiration Date for stockholders who own more than 10% of company's stock																	5 years from the grant date
Total stock ownership threshold where the award expiration period is reduced to five years from date of grant (in hundredths)																		10.00%
Maximum number of common stock shares to be issued (in shares)																			6.5	11.5			5.1
Total stock-based compensation expense	$ 16.9	$ 5.7	$ 16.7	$ 3.0	$ (0.9)	$ 9.5	$ 8.3	$ 4.4	$ 5.2	$ 5.6	$ 2.2	$ 2.0
Revaluation benefit from PRSU Granted					10.3
Grant date intrinsic value																											14.9
Target shares granted				0.3
Actual payout percentage, assumption and range				100.00%																								0.00%	200.00%
Maximum payout (percent)																											300.00%
Outstanding intrinsic value				13.6
Share-based payment award [Roll forward]
Beginning balance (in shares)				0.3	0.3					0.2	0.2
Granted (in shares)				0.3	0.4					0.2	0		0.2	0
Vested (in shares)				0	(0.4)					(0.2)	0
Forfeited (in shares)				(0.3)	0					0	0
Ending balance (in shares)				0.3	0.3	0.3				0.2	0.2	0.2
Weighted Average Grant Date Fair Value [Abstract]
Beginning balance (in dollars per share)				$ 58.52	$ 37.93					$ 32.03	$ 30.41
Granted (in dollars per share)				$ 39.34	$ 71.52					$ 45.56	$ 62.03
Vested (in dollars per share)				$ 0.00	$ 28.48					$ 30.49	$ 0.00
Forfeited (in dollars per share)				$ 56.92	$ 0.00					$ 0.00	$ 0.00
Ending balance (in dollars per share)				$ 39.04	$ 58.52	$ 37.93				$ 47.00	$ 32.03	$ 30.41
Aggregate intrinsic value of units outstanding										10.8
Option pricing model used to calculate the fair value of stock options granted	Black-Scholes option pricing model
Fair value assumptions and methodology [Abstract]
Expected volatility range of stock, minimum (in hundredths)	63.00%	49.00%	72.00%
Expected volatility range of stock, maximum (in hundredths)	72.80%	73.00%	74.00%
Expected life of option, range in years, minimum	2 years	2 years	3 years
Expected life of option, range in years, maximum	3 years	4 years	4 years
Risk-free interest rate range, minimum (in hundredths)	0.30%	0.30%	0.70%
Risk-free interest rate range, maximum (in hundredths)	0.60%	0.70%	1.70%
Expected dividend yield on stock, minimum (in hundredths)	0.60%	0.00%	0.00%
Expected dividend yield on stock, maximum (in hundredths)	0.90%	1.30%	0.70%
Share-based payment award options outstanding [Roll Forward]
Beginning Balance (in shares)															0.9	1.3					2.9	3.4
Granted (in shares)															0.6	0.4					0.6	0.4
Vested (in shares)															(0.8)	(0.8)
Exercised (in shares)																					(0.6)	(0.9)		(0.6)	(0.9)	(1.8)
Forfeited (in shares)															(0.1)	0					(0.1)	0
Ending balance (in shares)															0.6	0.9					2.8	2.9
Options exercisable (in shares)																					2.2
Unvested stock options additional disclosure [Abstract]
Beginning of period weighted average grant date fair value (dollars per share)															$ 23.49	$ 5.44
Granted weighted average grant date fair value (dollars per share)															$ 39.77	$ 35.75
Vested weighted average grant date fair value (dollars per share)															$ 19.71	$ 11.49
Forfeited weighted average grant date fair value (dollars per share)															$ 39.62	$ 0.00
Ending of period weighted average grant date fair value (dollars per share)															$ 42.16	$ 23.49
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Beginning balance weighted average exercise price (dollars per share)																					$ 17.00	$ 11.15
Granted weighted average exercise price (dollars per share)																					$ 39.77	$ 35.75
Exercised weighted average exercise price (dollars per share)																					$ 14.54	$ 12.61
Terminated weighted average exercise price (dollars per share)																					$ 39.62	$ 0.00
Ending balance weighted average exercise price (dollars per share)																					$ 21.73	$ 17.00
Options exercisable weighted average exercise price (dollars per share)																					$ 15.63
Ending balance weighted average remaining contractual term (in years)																					5 years 9 months 25 days
Options exercisable weighted average remaining contractual term (in years)																					4 years 10 months 17 days
Ending balance aggregate intrinsic value																					82.6
Options exercisable aggregate intrinsic value																					60.1
Total intrinsic value of options exercised	17.1	29.8	59.2
Total unrecognized stock-based compensation expense	10.5			2.4			5.2			2.9
Weighted Average Remaining Vesting Period (in years)	1 year 1 month 13 days			1 year 4 months 2 days			1 year 1 month 24 days			10 months 20 days
Cash Received from Exercise of Stock Options	$ 8.7	$ 11.4	$ 26.3