Schedule II (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance Beginning of Period	$ 2,084		$ 832		$ 1,005
Adduttuibs (Deductions) Charged	759		1,245		1,006
Changes to Reserves	1,013	[1]	(7)	[1]	1,179	[1]
Balance End of Period	1,830		2,084		832
Allowance for Sales Returns [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance Beginning of Period	21,620	[2]	7,423	[2]	5,718	[2]
Adduttuibs (Deductions) Charged	13,846	[2]	29,497	[2]	12,559	[2]
Changes to Reserves	24,613	[2]	15,300	[2]	10,854	[2]
Balance End of Period	10,853	[2]	21,620	[2]	7,423	[2]
Valuation Allowance of Deferred Tax Assets [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance Beginning of Period	12,919		11,242		10,811
Adduttuibs (Deductions) Charged	(1,593)		1,677		(719)
Changes to Reserves	147		0		1,150
Balance End of Period	$ 11,473		$ 12,919		$ 11,242

[1] Amounts deemed uncollectible, net of recoveries.

[2] Due to the nature of the Company's business and the complex invoices that result from the services provided, customers may withhold payments and attempt to renegotiate amounts invoiced. In addition, for some of the services provided, the Company's invoices are based on quotes that can either generate credits or debits when the actual revenue amount is known. Based on industry knowledge and historical trends, the Company records a revenue allowance accordingly. This practice causes the volume of activity flowing through the revenue allowance during the year to be higher than the balance at the end of the year. Increases in overall sales volumes and the expansion of the customer base in recent years have also increased the volume of additions and deductions to the allowance during the year, as well as increased the amount of the allowance at the end of the year.