Significant Accounting Policies Deferred Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Deferred Revenue Arrangement [Line Items]
Deferred Revenue	$ 40,020	$ 11,300	$ 40,020	$ 11,300	$ 36,188	$ 26,157	$ 8,100	$ 0
Deferred Revenue, Additions	6,962	3,554	22,076	11,830
Deferred Revenue, Revenue Recognized	(3,130)	$ (354)	(8,213)	$ (530)
Deferred Revenue, Current	16,045		16,045
Deferred Revenue, Noncurrent	$ 23,975		$ 23,975