Business Combination - SBC Materials International, Inc. (Details) - USD ($) $ in Thousands	Nov. 14, 2018	Mar. 30, 2018	Jun. 30, 2019	Dec. 31, 2018
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Goodwill			$ 74,213	$ 74,213
SBC Materials International, Inc.
Business Acquisition [Line Items]
Purchase price		$ 35,000
Payment at closing		20,000
Additional payment to be paid based on certain performance metrics		15,000
Goodwill, expected tax deductible amount			$ 2,025
Reduction in purchase price to be paid over time	$ 3,300
Present value of future payments, discount rate			2.50%
Present value of future payments			$ 11,014
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Cash acquired		17
Net working capital, excluding cash		21,255
Property, plant and equipment		5,300
Total purchase price		31,014
SBC Materials International, Inc. | Trade name intangible assets
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Intangible assets		694
SBC Materials International, Inc. | Customer relationship intangible assets
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Intangible assets		742
SBC Materials International, Inc. | Technology
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Intangible assets		1,972
SBC Materials International, Inc. | Non-compete and other agreements
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Intangible assets		289
Goodwill		$ 745