Selected Quarterly Financial Data (Unaudited) (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2011	Mar. 31, 2010	Jun. 30, 2011	Jun. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2011	Dec. 31, 2010
Selected quarterly financial data (unaudited) (Textual) [Abstract]
Minimum period for recognition of net gain loss from disposal of long term asset							1 year
Maximum period for recognition of lease revenue and cost of revenue on gross basis							1 year
Impact of Restatement in Cash Flow	$ 5.9	$ 0.2	$ 5.9	$ 0.2	$ 21.1	$ 0.3		$ 6.6