Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Components of loss before income taxes
U.S.	$ 14,981	$ (9,153)	$ (44,535)
Foreign	(864)	311	(38,770)
Income (loss) before income taxes	14,117	(8,842)	(83,305)
Current:
Federal			31
State	116	341	231
Foreign	4		224
Total current	120	341	486
Deferred:
Federal	293		(978)
State	445		(184)
Foreign			(1,238)
Total deferred	738		(2,400)
Total tax expense (benefit)	$ 858	$ 341	(1,914)
Federal income tax benefit, utilization of operating loss carryforwards			6,900
State and local income tax benefit, utilization of operating loss carryforwards			$ 1,500
Federal income tax rate	21.00%	21.00%	35.00%
Reconciliation of the income tax provision
Computed expected tax (benefit)	$ 2,964	$ (1,857)	$ (29,157)
Nondeductible expenses	3,087	5,674	13,420
Tax rate differential on foreign earnings	245	(56)	11,860
Joint ventures	(369)	947
Noncontrolling interest	4,114	1,133
Impact of federal income tax rate change			59,729
Tax credits	(10,314)	(6,603)	(27)
Other	665	985	2,376
Change in valuation allowance	466	118	(60,115)
Total tax expense (benefit)	858	341	(1,914)
Tax benefit related to exclusion of AFTC	10,500	6,100	$ 0
Deferred tax assets:
Accrued expenses	4,899	5,254
Alternative minimum tax and general business credits	6,651	6,801
Stock option expense	9,254	11,210
Other	1,456	1,998
Loss carryforwards	107,722	106,957
Total deferred tax assets	129,982	132,220
Less valuation allowance	(122,147)	(120,801)
Net deferred tax assets	7,835	11,419
Deferred tax liabilities:
Commodity swap contracts	(998)	(2,751)
Depreciation and amortization	(911)	(2,672)
Goodwill	(1,910)	(1,650)
Investments in joint ventures and partnerships	(4,754)	(4,346)
Total deferred tax liabilities	(8,573)	$ (11,419)
Net deferred tax liabilities	$ (738)