Discontinued Operations - Financial Results (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Discontinued Operations, Net of Taxes	$ 0	$ (300)	$ 2,300	$ (900)	$ 14,500	$ 7,900	$ 7,700	$ 300	$ 1,100	$ 30,400	$ 20,800
ASC | Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues									27,200	191,700	185,800
Operating expense									22,500	138,800	136,700
Depreciation expense									1,700	10,600	10,600
Selling, general and administrative expense									2,800	8,200	8,600
Total Expenses									27,000	157,600	155,900
Other (expense) income									(3,000)	3,800	(5,500)
(Loss) Income from Discontinued Operations Before Taxes									(2,800)	37,900	24,400
Income tax benefit (expense)									600	(7,500)	(3,600)
Net (Loss) Income from Discontinued Operations, Net of Taxes									(2,200)	30,400	20,800
Gain on Sale of Discontinued Operations, Net of Taxes		$ (300)	$ 3,600						3,300	0	0
Total Discontinued Operations, Net of Taxes									$ 1,100	$ 30,400	$ 20,800