Revenue (Tables)

12 Months Ended

Dec. 31, 2019

Revenue from Contract with Customer [Abstract]

Schedule of disaggregation of revenue

The table below presents the Company’s revenue disaggregated by revenue source (in thousands):

	Years Ended December 31,
	2017		2018		2019
Volume-related (1)	$	264,880	$	286,684	$	273,535
Station construction sales		51,854		25,501		23,120
AFTC		—		26,729		47,123
Compressor sales (2)		23,527		—		—
Other		1,338		7,505		287
Total revenue	$	341,599	$	346,419	$	344,065

(1) Includes changes in fair value of derivative instruments related to the Company’s commodity swap and customer fueling contracts. See Note 1 and Note 8 for more information about these derivative instruments. For the years ended December 31, 2018 and 2019, changes in the fair value of commodity swaps and customer fueling contracts amounted to a gain of $10.3 million and a loss of $6.6 million, respectively.

(2) The Company completed the CEC Combination (as defined in Note 4) during the year ended December 31, 2017 and no longer generates revenue from compressor sales.

Summary of contract balances

As of December 31, 2018 and 2019, the Company’s contract balances were as follows (in thousands):

	2018		2019
Accounts receivable, net	$	68,865	$	61,760
Contract assets - current	$	656	$	455
Contract assets - non-current		3,825		3,777
Contract assets - total	$	4,481	$	4,232
Contract liabilities - current	$	5,513	$	5,329
Contract liabilities - non-current		9,844		6,339
Contract liabilities - total	$	15,357	$	11,668