Significant Accounting Policies Deferred Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Deferred Revenue Arrangement [Line Items]
Deferred Revenue	$ 30,445	$ 26,157
Deferred Revenue, Additions	6,342
Deferred Revenue, Revenue Recognized	(2,054)
Deferred Revenue, Current	12,569
Deferred Revenue, Noncurrent	$ 17,876