Revenue Recognition (Additional Information) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained deficit	$ (524,009)	$ (524,009)	$ (500,044)
Revenue from Contract with Customer, Excluding Assessed Tax	16,557	69,510	$ 78,718	$ 81,479
Accounts receivable	700	700
Contract with customer, liability	$ 2,400	2,400
Increase (decrease) in contract with customer, liability		1,100
Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained deficit					$ 1,000
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		$ 1,600
Deferred revenue					$ 800