Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Financing program
Purchases of distributors financed	$ 1,579	$ 2,752	$ 1,696
Uncollectible outstanding receivables	0	55
Amount owed by distributors to third party financing company	943	1,714
Repossessed inventory required to be repurchased	$ 233	$ 41	$ 91
Interest rate swap
Derivative
Fixed interest rate (as a percent)	6.335%
Variable rate basis	LIBOR
Interest rate added to variable rate (as a percent)	4.25%
LIBOR floor (as a percent)	1.50%