Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Effective income tax rate reconciliation, excess tax benefit	$ 1,702	$ 1,510	$ 5,618	$ 4,205
Patents
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net of accumulated amortization			$ 144	$ 515