Revenue Recognition (Tables)

12 Months Ended

Dec. 31, 2019

Revenue from Contract with Customer [Abstract]

Schedule of Cumulative Effect of Changes to Balance Sheet

The cumulative effect of the changes made to our January 1, 2018 consolidated balance sheet for the adoption of ASC 606 were as follows:

	Balance at December 31, 2017			Adjustments Upon Adoption of ASC 606		Balance at January 1, 2018
Liabilities
Other accrued liabilities	$	5,098		(205	)	$	4,893
Equity
Accumulated deficit	(102,672		)	205		(102,467		)

The cumulative effect of the changes made to our January 1, 2019 consolidated balance sheet for the adoption of ASC 842 were as follows:

	Balance at December 31, 2018			Adjustments Upon Adoption of ASC 842			Balance at January 1, 2019
Assets
Right-of-use operating lease assets	$	—		$	1,592		$	1,592
Liabilities
Other accrued liabilities	6,099			(22		)	6,077
Operating lease liabilities - current	—			650			650
Operating lease liabilities - non-current	—			942			942
Equity
Accumulated deficit	(102,495		)	22			(102,473		)

Disaggregation of Revenue

The following table presents our revenues disaggregated by product technology:

	Twelve Months Ended  December 31,
	2019		2018		2017
Air Pollution Control
Technology solutions	$	10,640	$	35,176	$	24,422
Spare parts	1,031		1,083		1,022
Ancillary revenue	2,411		2,158		2,364
Total Air Pollution Control Technology	14,082		38,417		27,808
FUEL CHEM
FUEL CHEM technology solutions	16,385		18,118		17,358
Total Revenues	$	30,467	$	56,535	$	45,166

(1) As noted above, 2017 amounts have not been adjusted under the modified retrospective method.

The following table presents the timing of our revenue recognition:

	Twelve Months Ended   December 31,
	2019		2018		2017
Products transferred at a point in time	$	19,827	$	21,359	$	20,744
Products and services transferred over time	10,640		35,176		24,422
Total Revenues	$	30,467	$	56,535	$	45,166

(1) As noted above, 2017 amounts have not been adjusted under the modified retrospective method.

Revenue Disaggregated by Geography

The following table presents our revenues disaggregated by geography, based on the billing addresses of our customers:

	Twelve Months Ended  December 31,
	2019		2018		2017
United States	$	25,882	$	43,887	$	29,510
Foreign Revenues
South America	777		1,290		2,118
Europe	2,322		6,260		6,206
Asia	1,486		5,098		7,332
Total Foreign Revenues	4,585		12,648		15,656
Total Revenues	$	30,467	$	56,535	$	45,166

(1) As noted above, 2017 amounts have not been adjusted under the modified retrospective method.

Components of Accounts Receivable

The components of accounts receivable are as follows:

	As of
	December 31, 2019			December 31, 2018
Trade receivables	$	6,425		$	14,261
Unbilled receivables	1,857			5,540
Other short-term receivables	7			9
Allowance for doubtful accounts	(1,816		)	(1,411		)
Total accounts receivable	$	6,473		$	18,399