Discontinued Operations - Income (Loss) from Discontinued Operations (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
	Nov. 30, 2019	Dec. 31, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 31, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain from sale of discontinued operations, net of tax		$ 85,727	$ 137	$ 4,357	$ 5,937	$ 5,536	$ 7,969	$ 8,751	$ 6,709	$ 96,158	$ 28,965	$ 1,537
Discontinued Operations, Disposed of by Sale | Matane Plant
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues										127,561	177,419	20,917
Cost of sales										(106,572)	(124,396)	(18,618)
Gross margin										20,989	53,023	2,299
Selling, general and administrative expenses and other										(1,536)	(3,196)	173
Operating income (loss)										19,453	49,827	2,472
Interest expense										(3,957)	(4,485)	(482)
Other non-operating income										321	377	45
Income from discontinued operations before income taxes										15,817	45,719	2,035
Income tax expense										(4,096)	(16,754)	(498)
Income from discontinued operations, net of taxes										11,721	28,965	1,537
Gain from sale of discontinued operation, pre-tax										118,888	0	0
Income tax expense on gain										(34,451)	0	0
Gain from sale of discontinued operations, net of tax										84,437	0	0
Gain from sale of discontinued operations, net of tax										$ 96,158	$ 28,965	$ 1,537
Debt required to be repaid	$ 100,000