CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
CONDENSED CONSOLIDATED BALANCE SHEETS
Accounts receivable, allowances (in dollars)	$ 1,422	$ 1,565
Interest rate (as a percent)	3.00%	3.00%
Series A 3% Redeemable Convertible Preferred Stock, par value (in dollars per share)	$ 0.001	$ 0.001
Series A 3% Redeemable Convertible Preferred Stock, Authorized shares	100	100
Series A 3% Redeemable Convertible Preferred Stock, Issued shares	75	75
Series A 3% Redeemable Convertible Preferred Stock, outstanding shares	75	75
Series A 3% Redeemable Convertible Preferred Stock, Redemption value (in dollars)	$ 87,089	$ 87,089
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, Authorized shares	4,900	4,900
Preferred stock, Issued shares	0	0
Preferred stock, outstanding shares	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, Authorized shares	75,000	75,000
Common stock, Issued shares	32,130	31,949
Common stock, Outstanding shares	28,188	27,977
Treasury stock, shares	3,942	3,942