Valuation and Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accounts receivable allowances
Changes in valuation and qualifying accounts
Balance at Beginning of Period	$ 1,822	$ 1,148	$ 499
Additions	26,517	14,074	5,113
Deductions Charged to Reserves	(26,598)	(13,400)	(4,464)
Balance at End of Period	1,741	1,822	1,148
Rebates, fees and returns reserves
Changes in valuation and qualifying accounts
Balance at Beginning of Period	5,943	10,015	5,657
Additions	6,729	9,864	17,779
Deductions Charged to Reserves	(9,224)	(13,936)	(13,421)
Balance at End of Period	$ 3,448	$ 5,943	$ 10,015