Related party transactions (Details) - Affiliated Entities - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
CP&P Joint Venture
Related Party Transaction [Line Items]
Sales of products to related party	$ 500	$ 5
Purchased goods and services from related party	$ 100	$ 126
Lone Star
Related Party Transaction [Line Items]
Payment of certain covered tax benefits buy the Company, percentage	85.00%