Uncertain Tax Positions (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Uncertain Tax Positions [Abstract]
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 3,400,000	$ 2,100,000
Reconciliation of unrecognized tax benefits [Roll Forward]
Balance, beginning of period	2,060,000
Gross increases - current year tax positions	1,343,000
Gross increases - tax positions from prior periods	4,000
Balance, end of period	3,407,000
Interest and penalties accrued [Abstract]
Accrual for interest and penalties			100,000
Tax credits and other various deductions [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Estimated change in unrecognized tax benefits expected within the next twelve months	$ 400,000