Schedule II - Valuation and Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Allowance for Bad Debts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 1,066	$ 1,175	$ 1,370
Charged to costs and expenses	3,935	397	119
Charged to other accounts	0	0	0
Deductions	(3,818)	(506)	(314)
Balance at end of period	1,183	1,066	1,175
Sales Returns and Allowance [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	3,980	3,356	2,974
Charged to costs and expenses	291	721	647
Charged to other accounts	0	0	0
Deductions	(174)	(97)	(265)
Balance at end of period	4,097	3,980	3,356
Deferred Tax Asset Valuation Allowance [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	226	1,058	2,069
Charged to costs and expenses	0	226	278
Charged to other accounts	0	0	0
Deductions	(226)	(1,058)	(1,289)
Balance at end of period	$ 0	$ 226	$ 1,058