Warranty Liability (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Warranty liability
Period of warranty history used in estimating warranty costs (in years)			5 years
Company's warranty liability:
Balance at the beginning of the period	$ 3,506	$ 2,270	$ 4,188	$ 3,399
Warranty provision	643	1,244	773	1,631
Claims paid/settlements	(184)	(444)	(996)	(1,960)
Balance at the end of the period	$ 3,965	$ 3,070	$ 3,965	$ 3,070
Snow and ice control equipment
Warranty liability
Warranty period (in years)			2 years
Parts and accessories
Warranty liability
Warranty period (in years)			1 year
Certain snowplows
Warranty liability
Warranty period (in years)			1 year