CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net income (loss)	$ (94,155)	$ (11,529)	$ 13,259
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	45,184	47,682	49,625
Provision for credit losses and inventory	1,257	2,662	2,586
Stock-based compensation expense	14,994	2,957	3,880
Stock-based sales incentive charges	83,641	0	0
Change in fair value of derivative instruments	3,490	(2,175)	5,545
Amortization of discount and debt issuance cost	20	(46)	(728)
Loss (gain) on disposal of property and equipment	1,365	(2,875)	(2,536)
Loss on extinguishment of debt	39	1,249
Gain from sale of certain assets of subsidiary	(3,885)	(1,063)	(7,455)
Gain from formation of equity method investment		(700)
Loss from equity method investments	430	161	119
Non-cash lease expense	2,945	2,756	3,234
Deferred income taxes	69	120	738
Expense reimbursement from JV	1,640
Changes in operating assets and liabilities:
Accounts and other receivables	(24,260)	53,784	(63,408)
Inventory	(5,704)	108	3,439
Prepaid expenses and other assets	(10,498)	5,275	(16,617)
Operating lease liabilities	(3,053)	(3,141)	(3,786)
Accounts payable	6,615	(9,337)	9,316
Deferred revenue	4,550	(10,976)	(3,528)
Accrued liabilities and other	16,614	(13,871)	18,596
Net cash provided by operating activities	41,298	61,041	12,279
Cash flows from investing activities:
Purchases of short-term investments	(324,170)	(74,292)	(171,080)
Maturities and sales of short-term investments	223,991	101,850	180,704
Purchases of and deposits on property and equipment	(23,075)	(13,273)	(27,088)
Disbursements for loans receivable for RNG production projects	(3,905)	(535)
Payments on and proceeds from sales of loans receivable	421	1,567	608
Cash received from sale of certain assets of subsidiary, net	887	4,830	7,582
Investments in other entities	(78,919)	(650)
Payment and deposits on equipment and manure rights for RNG production projects	(5,830)
Proceeds from disposal of property and equipment	2,941	4,673	7,772
Net cash provided by (used in) investing activities	(207,659)	24,170	(1,502)
Cash flows from financing activities:
Issuance of common stock	204,455	1,683	309
Repurchase of common stock	(2,916)	(14,647)
Fees paid for issuance of common stock	(6,534)
Fees paid for debt issuance costs	(1,277)	(131)	(123)
Proceeds for Adopt-a-Port program	5,815
Repayment of proceeds for Adopt-a-Port program	(360)
Proceeds from debt instruments	4,400	65,860	15,294
Proceeds from revolving line of credit	1,450
Repayments of borrowing under revolving line of credit	(1,450)
Repayments of debt instruments and finance lease obligations	(50,737)	(70,399)	(7,795)
Payments of debt extinguishment costs	(14)	(1,023)
Net cash (used in) provided by financing activities	152,832	(18,657)	7,685
Effect of exchange rates on cash, cash equivalents and restricted cash	8	201	136
Net increase (decrease) in cash, cash equivalents and restricted cash	(13,521)	66,755	18,598
Cash, cash equivalents and restricted cash, beginning of period	119,977	53,222	34,624
Cash, cash equivalents and restricted cash, end of period	106,456	119,977	53,222
Supplemental disclosure of cash flow information:
Income taxes paid	15	8	36
Interest paid, net of $441, $57 and $0 capitalized, respectively	$ 3,907	$ 5,622	$ 6,788