Commitments and Contingencies (Details) (USD $)	12 Months Ended				3 Months Ended			6 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 13, 2011	Dec. 31, 2011 Class Action Complaint [Member]	Dec. 31, 2010 Class Action Complaint [Member]	Dec. 31, 2008 Class Action Complaint [Member]	Jun. 30, 2009 Class Action Complaint [Member]	Jan. 15, 2010 Class Action Complaint [Member]	Sep. 28, 2010 Class Action Complaint [Member]	Dec. 31, 2009 Class Action Complaint [Member]	Jan. 13, 2005 Class Action Complaint [Member]
Loss Contingencies [Line Items]
Original District Court judgment, pre-judgment interest rate (in hundredths)												5.00%
Original District Court judgment, back pay awarded to plaintiffs												$ 3,400,000
Original District Court judgment, estimated attorney fees to be awarded to plaintiffs, maximum												2,500,000
Interim District Court judgment, attorney fees and costs awarded to plaintiffs							5,800,000
Loss provision recorded during the period					900,000	1,000,000	6,000,000	5,000,000
Final District Court judgment, damages awarded to plaintiffs									3,300,000
Final District Court judgment, pre-judgment interest awarded to plaintiffs									2,200,000
Final District Court judgment, post-judgment interest rate (in hundredths)									0.41%
Previous estimate of total liability for damages and interest									5,200,000
Settlement of aggregate attorney fees					2,700,000
Pre-tax impact, net					1,800,000
Number of days plaintiffs were given to submit supplemental request									14D
Motion for supplemental award for attorney's fees, cost and expenses, amount sought									700,000
Final District Court judgment, attorney's fees, costs, and expenses awarded to plaintiffs										700,000	1,000,000
Aggregate product warranty liability [Roll Forward]
Beginning balance	3,620,000	4,220,000		4,847,000
Claims paid or accrued	(3,032,000)	(3,213,000)
Additional warranties issued	4,225,000	3,244,000
Revisions in estimates	67,000	(678,000)
Foreign currency translation	(33,000)	47,000
Ending balance		3,620,000	4,220,000	4,847,000
Future minimum rental payments for operating leases [Abstract]
2012	2,469,000
2013	3,714,000
2014	3,005,000
2015	2,359,000
2016	1,446,000
Thereafter	4,473,000
Expense for rentals and leases [Abstract]
Expense for rentals and leases	9,900,000	7,800,000	6,000,000
Contractual commitments for capital expenditures [Abstract]
Contractual commitments for capital expenditures expected to be paid in next fiscal year	56,000,000
Contractual commitments for capital expenditures expected to be paid in second year				$ 3,000,000