Revenue Recognition Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Revenue Recognition and Deferred Revenue [Abstract]
Contract with Customer, Asset, Gross	$ 14,300	$ 14,300	$ 11,300
Contract with Customer, Liability	142,400	142,400	71,100
Contract with customer, revenue recognized	2,800	(75,618)
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred Revenue, Current	94,546	94,546	41,438
Retained Earnings (Accumulated Deficit)	(469,155)	(469,155)	$ (337,873)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred Revenue	21,000	21,000
Deferred Revenue, Current	9,000	9,000
Retained Earnings (Accumulated Deficit)	$ 15,000	$ 15,000