Revenues - Narrative (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Accounts receivable	$ 135,217	$ 144,767
Contract assets	1,700	1,100
Contract liabilities	$ 24	$ 855

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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