Stock Compensation Plan (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended				9 Months Ended			3 Months Ended		9 Months Ended			9 Months Ended						9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Stock Options	Dec. 31, 2011 Stock Options	Sep. 30, 2012 Stock Options Non-employee members of the board of directors	Sep. 30, 2012 RSUs	Sep. 30, 2012 RSUs Non-employee members of the board of directors	Sep. 30, 2012 Stock options and SARs	Sep. 30, 2011 Stock options and SARs	Sep. 30, 2012 Stock options and SARs	Sep. 30, 2011 Stock options and SARs	Dec. 31, 2011 Stock options and SARs	Sep. 30, 2012 Nonqualified stock options President and chief operating officer	Sep. 30, 2012 Nonqualified stock options President and chief operating officer Vesting on December 31, 2014	Sep. 30, 2012 Nonqualified stock options President and chief operating officer Vesting on December 31, 2015	Sep. 30, 2012 Nonqualified stock options President and chief operating officer Vesting on December 31, 2016	Sep. 30, 2012 Omnibus Plan	Dec. 31, 2004 Omnibus Plan	Sep. 30, 2012 LTCP Stock Options Participants	Sep. 30, 2012 LTCP RSUs Non-employee members of the board of directors	Sep. 30, 2012 LTCP Performance units
Stock Compensation Plan
Shares of common stock reserved for issuance															125,000				760,000	3,500,000
Par value of shares of common stock (in dollars per share)																				$ 0.01
Excess tax benefits related to the exercise or vesting of stock-based awards			$ 5.1	$ 0.8
Stock-based compensation expense and related income tax benefits
Stock-based compensation expense	0.9	0.9	3.9	3.1	1.0			2.9
Income tax benefit	(0.3)	(0.4)	(1.5)	(1.2)
Stock-based compensation, net of Income tax benefit	0.6	0.5	2.4	1.9
Compensation costs related to equity awards and amounts recognized
Unrecognized compensation cost at the beginning of the period					0.8			2.4
Grant date fair value of current year grants					2.0
Grant date fair value of current year grants								4.1
Compensation expense recognized	(0.9)	(0.9)	(3.9)	(3.1)	(1.0)			(2.9)
Estimated forfeitures for awards granted in prior years								0.1
Unrecognized compensation cost at the end of the period					1.8			3.7
Expected amortization period					3 years 2 months 12 days			1 year 9 months 18 days
Shares of common stock awarded							1,570														96,000
Weighted-average exercise price (in dollars per share)												$ 24.14			$ 24.09
Weighted-average grant date fair value (in dollars per share)												$ 8.13			$ 9.55
Fair value assumptions
Expected term in years												4 years 10 months 24 days
Risk free interest rate (as a percent)												1.10%
Volatility (as a percent)												45.40%
Dividend yield (as a percent)												2.00%
Additional disclosures
Expiration period															10 years
Vesting Rights (as Percent)																25.00%	50.00%	100.00%
Aggregate pre-tax intrinsic value of stock options and SARs exercised										1.0	1.1	4.5	1.4
Number of options exercisable (in shares)										1,390,000		1,390,000		1,660,000
Aggregate intrinsic value of options exercisable										8.4		8.4		4.7
Vested (in shares)												270,000
Aggregate grant date fair value												1.2
Shares outstanding that vested and would have been exercisable had the participants reached retirement age																					45,000
Aggregate grant date fair value of options subject to accelerated vesting																					0.4
Vested or expected to vest (in shares)										1,730,000		1,730,000		2,035,000
Weighted average grant date fair value of awards vested or expected to vest										$ 9.51		$ 9.51		$ 9.03
Vested or expected to vest, aggregate intrinsic value										10.8		10.8		8.1
Unvested stock options outstanding (in shares)					345,000	395,000
Weighted-average grant date fair value of unvested stock options (in dollars per share)					$ 9.73	$ 5.25
Percentage of target to be awarded, low end of range																							40.00%
Percentage of target to be awarded, high end of range																							200.00%
Common stock earned as a percentage of the performance unit target																							170.00%
Market price at grant date of performance units									$ 27.05														$ 23.09
Granted									12,025														103,000
Vesting period (in years)									1 year
Units issued in lieu of dividends (in shares)									664
Vested (in shares)																						635,000
Intrinsic value of units vested																						$ 15.0