Employee Benefit Plans (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Postretirement Benefits [Line Items]
Contributions to the defined contribution plans	$ 3,000	$ 3,000	$ 2,700
Other, net of income taxes	(2,644)	(298)	(1,128)
Pension Plan [Member]
Postretirement Benefits [Line Items]
Other, net of income taxes	2,600	300	$ 1,100
Projected benefit obligation	50,049	53,489
Postretirement Health Coverage [Member]
Postretirement Benefits [Line Items]
Projected benefit obligation	1,500	1,700
Canada [Member] | Pension Plan [Member]
Postretirement Benefits [Line Items]
Funded status of the Pension Plans	2,000	2,300
U.S. Liquids [Member] | Pension Plan [Member]
Postretirement Benefits [Line Items]
Funded status of the Pension Plans	$ 8,800	$ 8,100