Postretirement Medical Benefits (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Employee	Dec. 31, 2017 USD ($)		Dec. 31, 2016 USD ($)
Net Periodic benefit costs related to retirement plans [Abstract]
Net periodic benefit cost (credit)	$ (262)	$ (653)	[1]	$ 722	[1]
United States [Member]
Defined Benefit Plan [Abstract]
Number of former union employees covered by the plan | Employee	20
Postretirement Benefits [Member]
Net Periodic benefit costs related to retirement plans [Abstract]
Net periodic benefit cost (credit)	$ (262)	(653)	[1]	722	[1]
Summary of expected future benefit payments [Abstract]
2019	39
2020	36
2021	32
2022	29
2023	25
Years 2024 - 2028	76
Postretirement Benefits [Member] | United States [Member]
Change in benefit obligation [Roll Forward]
Benefit obligation at beginning of year	672	1,574
Service cost	0	0	[1]	0	[1]
Interest cost	6	8	[1]	11	[1]
Benefits paid	(201)	(429)
Actuarial gain	(247)	(481)
Benefit obligation at end of year	230	672		1,574
(Unfunded) status of the plan	(230)	(672)
Amounts recognized in the balance sheet [Abstract]
Accrued postretirement benefit liabilities	230	672
Accumulated other comprehensive (income) loss (pre-tax) related to [Abstract]
Unrecognized net actuarial losses (gains)	(173)	(194)
Net Periodic benefit costs related to retirement plans [Abstract]
Service cost	0	0	[1]	0	[1]
Interest cost	6	8	[1]	11	[1]
Actuarial net (gain) loss	(268)	(661)	[1]	809	[1]
Net periodic benefit cost (credit)	$ (262)	$ (653)	[1]	$ 820	[1]
Actuarial assumptions used to determine costs and benefit obligations related to postretirement plan [Abstract]
Discount rate	0.00%	0.00%		0.00%
Postretirement Benefits [Member] | CANADA [Member]
Change in benefit obligation [Roll Forward]
Service cost	$ 0	$ 0	[1]	$ 0	[1]
Interest cost	0	0	[1]	2	[1]
Net Periodic benefit costs related to retirement plans [Abstract]
Service cost	0	0	[1]	0	[1]
Interest cost	0	0	[1]	2	[1]
Amortization of prior service cost	0	0	[1]	(54)	[1]
Actuarial net (gain) loss	0	0	[1]	(46)	[1]
Net periodic benefit cost (credit)	$ 0	$ 0	[1]	$ (98)	[1]
Actuarial assumptions used to determine costs and benefit obligations related to postretirement plan [Abstract]
Discount rate				3.00%

[1] Net periodic benefit credit (cost) has been reclassified from selling, general and administrative expenses to other non-operating income (expense), net on our consolidated statement of operations upon adoption of ASU 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, see Note 1, "Summary of Significant Accounting Policies" for additional information.