Commitments and Contingencies (Details Textual) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		12 Months Ended
	Jun. 30, 2006 sqft Y	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2011	Dec. 31, 2010	Jun. 22, 2006
Commitments and Contingencies (Textual) [Abstract]
Number of years of lease of corporate headquarters	7
Area of leased office building	192,000
Purchase price of property at end of Lease Term						$ 41.2
Percentage of Lease Balance as final payment end of lease term						82.00%
Self insurance liabilities recorded in Accrued expenses		63.3		63.3	64.6
Change in estimates associated with pre-existing liabilities			2.5	(0.8)	(6.2)
Changes in estimates associated with pre-existing liabilities			1.4
Estimated liabilities for future claims		$ 1.4