Statement of Shareholders' Equity (USD $) In Thousands, unless otherwise specified	12 Months Ended							12 Months Ended				12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Common Stock [Member]	Dec. 31, 2012 Common Stock [Member]	Dec. 31, 2011 Common Stock [Member]	Dec. 31, 2010 Common Stock [Member]	Dec. 31, 2013 Additional Paid-in Capital [Member]	Dec. 31, 2012 Additional Paid-in Capital [Member]	Dec. 31, 2011 Additional Paid-in Capital [Member]	Dec. 31, 2010 Additional Paid-in Capital [Member]	Dec. 31, 2013 Accumulated Other Comprehensive Income (Loss) [Member]	Dec. 31, 2012 Accumulated Other Comprehensive Income (Loss) [Member]	Dec. 31, 2011 Accumulated Other Comprehensive Income (Loss) [Member]	Dec. 31, 2013 Retained Earnings [Member]	Dec. 31, 2012 Retained Earnings [Member]	Dec. 31, 2011 Retained Earnings [Member]	Dec. 31, 2010 Retained Earnings [Member]
Shares, Issued				32,953	32,367	31,883	31,417
Stockholders' Equity Attributable to Parent	$ 279,003	$ 270,489	$ 221,778	$ 33	$ 32	$ 32	$ 31	$ 415,739	$ 409,974	$ 405,505	$ 393,456	$ (1,795)	$ (1,085)	$ (1,462)	$ (134,974)	$ (138,432)	$ (182,297)	$ (207,523)
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures				586	484	466
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	1,012	257	257	1	0	1		1,011	257	256		0	0	0	0	0	0
Net Income (Loss) Attributable to Parent	3,458	43,865	25,226												3,458	43,865	25,226
Share-based Compensation	4,106	4,001	4,802					4,106	4,001	4,802
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	648	211	528					648	211	528
Issuance of Convertible Note										13,963
Adjustments to Additional Paid in Capital, Warrant Issued										7,007
Purchase of convertible note hedge										(14,507)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent	(660)	394	(683)									(660)	394	(683)
Unrealized Gain (Loss) on Investments	$ (50)	$ (17)	$ 151									$ (50)	$ (17)	$ 151