Discontinued Operations - Financial Information of Discontinued Operations (Details) - Discontinued Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue	$ 50,667	$ 62,820	$ 111,206	$ 124,606
Cost of revenue	44,512	80,746	92,783	141,366
Corporate general and administrative expense	3,716	2,975	9,432	5,069
Interest expense (income), net	10	(97)	(40)	(172)
Impairment of assets held for sale			100,000	0
Total cost and expenses	48,238	83,624	202,175	146,263
Earnings (loss) before taxes from Disc Ops	2,429	(20,804)	(90,969)	(21,657)
Income tax expense (benefit)	485	(4,213)	1,942	(4,252)
Net earnings (loss) from Disc Ops	1,944	(16,591)	(92,911)	(17,405)
AMECO
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue	50,667	62,820	111,206	124,606
Cost of revenue	44,512	80,746	92,783	141,366
Corporate general and administrative expense	37	71	51	150
Interest expense (income), net	10	(97)	(40)	(172)
Impairment of assets held for sale			100,000	0
Total cost and expenses	44,559	80,720	192,794	141,344
Earnings (loss) before taxes from Disc Ops	6,108	(17,900)	(81,588)	(16,738)
Income tax expense (benefit)	485	(3,542)	1,942	(3,115)
Net earnings (loss) from Disc Ops	5,623	(14,358)	(83,530)	(13,623)
Other
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue	0	0	0	0
Cost of revenue	0	0	0	0
Corporate general and administrative expense	3,679	2,904	9,381	4,919
Interest expense (income), net	0	0	0	0
Impairment of assets held for sale			0	0
Total cost and expenses	3,679	2,904	9,381	4,919
Earnings (loss) before taxes from Disc Ops	(3,679)	(2,904)	(9,381)	(4,919)
Income tax expense (benefit)	0	(671)	0	(1,137)
Net earnings (loss) from Disc Ops	$ (3,679)	$ (2,233)	$ (9,381)	$ (3,782)