Stock-Based Compensation (Details 3) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of information regarding stock options outstanding
Options outstanding, Number of Shares	3,099,155	3,267,838	4,000,526
Options outstanding, Weighted Average Exercise Price	$ 6.65	$ 6.61
Options outstanding, Weighted Average Remaining Contractual Life (years)	5 years 6 months 22 days	5 years 6 months 11 days
Options outstanding, Aggregate Intrinsic Value	$ 1.3	$ 1.3
Options vested and expected to vest using estimated forfeiture rates, Number of Shares	2,993,600	3,151,950
Options vested and expected to vest using estimated forfeiture rates, Weighted Average Exercise Price	$ 6.66	$ 6.62
Options vested and expected to vest using estimated forfeiture rates, Weighted Average Remaining Contractual Life (years)	5 years 6 months 7 days	5 years 5 months 9 days
Options vested and expected to vest using estimated forfeiture rates, Aggregate Intrinsic Value	1.3	1.3
Options exercisable, Number of Shares	2,265,176	2,377,683
Options exercisable, Weighted Average Exercise Price	$ 6.97	$ 6.99
Options exercisable, Weighted Average Remaining Contractual Life (years)	5 years 7 days	4 years 7 months 10 days
Options exercisable, Aggregate Intrinsic Value	$ 1.0	$ 0.8