Fair Value Measurements (Details 2) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings	$ 2,101	$ (703)
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	0	18,912	$ 18,912	$ 22,815
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	$ (21,013)	$ (3,200)