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Revenue Recognition - Other Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle					$ 1,700
Revenues	$ 110,630	$ 100,008	$ 329,319	$ 305,790
Contract with customer, liability, revenue recognized	$ 300		$ 900
Accounting Standards Update 2014-09 \| Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle					$ 100