Stock-Based Compensation (Details 3) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Weighted-Average Grant Date Fair Value
Cash received from stock option exercises and employee stock purchases	$ 8.9
Cash used for shares withheld to satisfy employee tax obligations for NQOs exercised and RSUs converted	7.3
Shares authorized for future grant under stock plan (in shares)	2,200,000
RSUs
Summary of the Company's RSU activity
Outstanding at the beginning of the period	1,000,000	900,000	400,000
Granted	300,000	400,000	700,000
Issued	(400,000)	(300,000)	(100,000)
Forfeited			(100,000)
Outstanding at the end of the period	900,000	1,000,000	900,000
Weighted-Average Grant Date Fair Value
Outstanding at the beginning of the period	$ 11.76	$ 12.21	$ 20.17
Granted	$ 20.63	$ 11.41	$ 8.42
Issued	$ 12.51	$ 12.91	$ 20.09
Forfeited	$ 11.62	$ 10.00	$ 9.46
Outstanding at the end of the period	$ 14.49	$ 11.76	$ 12.21
Unrecognized compensation cost	4.3
RSUs | Minimum
Weighted-Average Grant Date Fair Value
Period over which unrecognized compensation costs will be recognized (in years)	1
RSUs | Maximum
Weighted-Average Grant Date Fair Value
Period over which unrecognized compensation costs will be recognized (in years)	3
PRSUs
Summary of the Company's RSU activity
Outstanding at the beginning of the period	600,000	500,000	400,000
Granted	100,000	300,000	400,000
Issued		(100,000)	(100,000)
Forfeited		(100,000)	(200,000)
Outstanding at the end of the period	700,000	600,000	500,000
Weighted-Average Grant Date Fair Value
Outstanding at the beginning of the period	$ 9.77	$ 11.18	$ 19.74
Granted	$ 19.02	$ 10.95	$ 7.83
Issued	$ 22.18	$ 17.03	$ 20.97
Forfeited	$ 11.65	$ 7.37	$ 21.11
Outstanding at the end of the period	$ 11.53	$ 9.77	$ 11.18
Unrecognized compensation cost	$ 5.2
Service period restriction after completing performance period for awards issued prior to 2009 (in years)	1
Performance period for awards issued prior to 2009 (in years)	2
Performance period (in years)	3 years	3 years	3 years
Current projections and performance targets estimated additional performance shares issuable	600,000
PRSUs | Minimum
Weighted-Average Grant Date Fair Value
Period over which unrecognized compensation costs will be recognized (in years)	1
PRSUs | Maximum
Weighted-Average Grant Date Fair Value
Period over which unrecognized compensation costs will be recognized (in years)	3
Employee stock purchase plan
Weighted-Average Grant Date Fair Value
Maximum contribution by eligible employees as percentage of base earnings (as a percent)	10.00%
Common stock purchase price as percentage of fair market value (as a percent)	85.00%
Shares purchased under employee stock purchase plan (in shares)	30,585	45,370