Restructuring Charges (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Changes in restructuring liability
Severance and related costs	$ 2,300	$ 100	$ 18	$ 2,621	$ 2,334
Severance
Restructuring charges
Stock option modification				100
Changes in restructuring liability
Balance at the beginning of the period			481	43	659
Severance and related costs			(2)	2,565	2,334
Cash payments			$ (479)	(2,127)	(2,950)
Balance at the end of the period				$ 481	$ 43