Composition of Certain Financial Statement Items (Accrued Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Accrued Liabilities, Current [Abstract]
Accrued payroll and employee-related expenses	$ 8,015	$ 11,007
Accrued sales, income, and excise taxes	1,320	1,659
Deferred rent	1,150	1,204
Accrued clinical study expense	1,120	872
Accrued royalties	576	571
Accrued legal costs	537	134
Employee stock purchase plan liability	533	801
Contingent consideration, current portion	500	500
Other accrued expenses	3,397	3,286
Less: long-term portion	(1,162)	(1,215)
Accrued liabilities: current portion	$ 15,986	$ 18,819