Summary of Significant Accounting Policies (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2012 Segment	Dec. 31, 2011	Dec. 31, 2010
Summary of Significant Accounting Policies (Textual) [Abstract]
Number of business segments	4
Impairments of long-lived assets	$ 0	$ 0	$ 0
Period for warranties for rental equipment	90 days
Period for warranties for equipment manufactured	1 year
Total advertising expenses	2,500,000	2,100,000	1,700,000
Goodwill and intangible assets	37,200,000
Intangible assets related to customer relationships amortized year	11 years
Goodwill and trade name intangible assets	33,400,000	33,400,000
Unbilled receivables related to end-of-lease services	17,400,000	17,200,000
Period for Credit	30 days
Estimated fair value notes payable	106,000,000	107,000,000
Recorded fair value of notes payable	100,000,000	100,000,000
Non cash share based compensation	3,840,000	5,221,000	4,227,000
Tax benefit relate to aforementioned stock based compensation expenses	1,500,000	2,000,000	1,600,000
Share - based compensation	$ 2,400,000	$ 3,200,000	$ 2,600,000
Diluted share	$ 0.09	$ 0.13	$ 0.11
Weighted average grant date fair value	$ 10.28	$ 9.68	$ 8.12