Inventories (Details) (USD $)	Dec. 31, 2011	Dec. 31, 2010
Inventories [Abstract]
Raw materials	$ 30,485,000	$ 32,586,000
Service parts	13,412,000	9,818,000
Work in process	316,000	92,000
Finished goods	59,409,000	40,161,000
Inventories	103,622,000	82,657,000
Service parts inventories not expected to be sold within next 12 months	$ 4,300,000	$ 4,100,000