Stock Plans (Details Textual) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended								12 Months Ended				12 Months Ended
	Sep. 30, 2010	Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 Omnibus Incentive 2006 Plan [Member]	Dec. 31, 2011 LTIP Restricted Stock Units [Member]	Dec. 31, 2008 LTIP Restricted Stock Units [Member]	Dec. 31, 2010 LTIP Restricted Stock Units [Member]	Sep. 30, 2010 LTIP Restricted Stock Units [Member]	Dec. 31, 2011 LTIP Stock Options [Member]	Dec. 31, 2009 LTIP Stock Options [Member]	Dec. 31, 2008 LTIP Stock Options [Member]	Aug. 06, 2009 LTIP Stock Options [Member]	Dec. 31, 2011 Equity Incentive Plan Employee Stock Option [Member] Y	Dec. 31, 2010 Equity Incentive Plan Employee Stock Option [Member]	Dec. 31, 2009 Equity Incentive Plan Employee Stock Option [Member]	Dec. 31, 2011 Equity Incentive Plan Restricted Stock [Member]	Dec. 31, 2010 Equity Incentive Plan Restricted Stock [Member]	Dec. 31, 2009 Equity Incentive Plan Restricted Stock [Member]	Dec. 31, 2011 Restricted Stock Awards for Certain Management [Member]	Dec. 31, 2011 Performance Accelerated Restricted Stock Unit Program [Member]	Dec. 31, 2010 Performance Accelerated Restricted Stock Unit Program [Member]	Dec. 31, 2009 Performance Accelerated Restricted Stock Unit Program [Member]
Stock Plans (Textual) [Abstract]
Maximum grant of stock options, restricted stock, and restricted stock units to directors and employees					2,690,000
Maximum number of shares other than options or stock appreciation rights granted for awards					1,350,000
Expiration period for stock option awards					10 years					10 years
Exercisable period from the date of grant for stock option granted to non employee directors					1 year
Exercisable period from the date of grant for stock option granted to Employees, Minimum					1 year
Exercisable period from the date of grant for stock option granted to Employees, Maximum					4 years
Weighted average remaining contractual term of options outstanding														4.7
Weighted average remaining contractual term of options exercisable														3.2
Aggregate intrinsic value of options outstanding														$ 7.1
Aggregate intrinsic value of options exercisable														3.5
Weighted average grant date fair value														$ 19.94	$ 11.56	$ 5.38
Total intrinsic value of options exercised														2.40	7.50	0.01
Vesting period from the date of grant for restricted stock awards granted to employees, Minimum																	1 year
Vesting period from the date of grant for restricted stock awards granted to employees, maximum																	4 years
Vesting period from the date of grant for restricted stock awards granted to non-employee directors																	1 year
Weighted-average grant-date fair value of restricted stock awards granted						$ 0.00											$ 33.26	$ 21.97	$ 11.73
Vesting period of LTIP restricted stock units						P4Y
Vesting period from the date of grant										Two to four years										May vest in 2014
Fair value of restricted stock awards vested																	3.3	2.5	0.8
Stock options granted										0		650,000		204,600
Exercise price of common stock on the grant date										$ 0.00		$ 38.00		$ 34.30
Market price of common stock on the grant date												$ 31.02
Restricted stock award, Outstanding						281,500		281,500									633,647	471,894
Number of stock option surrender and cancelled under stock option cancellation agreement											510,000					472,200
Stock option exercise price under stock option cancellation agreements													$ 38.00
Minimum range of stock option exercise price under cancellation agreements																$ 40.22
Maximum range of stock option price under cancellation agreements																$ 56.14
Restricted stock award granted by Company						0	449,500										281,780			67,400	0	0	0
Percentage of the long term incentive plan restricted stock units vesting on the date of amendment									25.00%
Percentage of units vesting on the February 4, 2012 based on the extent of satisfaction of performance criteria						75.00%
Percentage of units vesting on the December 31, 2012 provided recipient remain employed						25.00%
Additional Stock Plans (Textual) [Abstract]
Common stock issued		15,098	13,044	33,172
Previously unrecognized compensation cost related to cancelled stock options, recorded				3.0
Weighted average period to recognize compensation cost		2.3
Cash received from stock option exercises		4.5	25.7	0.1
Percentage of closing price for purchase price of common stock under employee stock purchase plan		95.00%
Unrecognized compensation cost		18.7
Compensation Cost		10.2	10.1	10.0
Tax benefit recognized from all stock-based employee compensation plans		3.7	3.6	3.6
Employee service share based compensation tax benefit realized from share based compensation plans		(0.7)	(2.3)	3.1
Common stock purchased under employee stock purchase plans average price		$ 24.41	$ 27.16	$ 12.48
Additional compensation cost due to modifications	$ 2.5		$ 2.8