Revenue

Disaggregation of Revenue

The following table summarizes net sales by end market:



(in thousands)	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
End Market	2019		2018		2019		2018
Energy	$	64,331	$	48,481	$	162,224	$	139,062
Industrial	37,020		52,367		142,267		146,137
Transportation	37,161		35,470		88,492		72,605
Total	$	138,512	$	136,318	$	392,983	$	357,804

The following table summarizes net sales by geographic area:



(in thousands)	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
Geographic Area	2019		2018		2019		2018
North America	$	125,971	$	120,955	$	343,593	$	312,346
Pacific Rim	6,744		10,913		30,173		32,768
Europe	4,329		3,012		12,712		9,948
Other	1,468		1,438		6,505		2,742
Total	$	138,512	$	136,318	$	392,983	$	357,804

Contract Balances

Most of the Company’s contracts are for a period of less than one year; however, certain long-term manufacturing and extended warranty contracts extend beyond one year. The timing of revenue recognition may differ from the time of invoicing to customers and these timing differences result in contract assets, or contract liabilities on the Company’s Consolidated Balance Sheet. Contract assets include amounts related to the contractual right to consideration for completed performance when the right to consideration is conditional. The Company records contract liabilities when cash payments are received or due in advance of performance. Contract assets and contract liabilities are recognized at the contract level.



(in thousands)	As of
	September 30, 2019			December 31, 2018
Short-term contract assets (included in Prepaid expenses and other current assets)	$	4,038		$	2,926
Short-term contract liabilities (included in Other accrued liabilities)	(15,959		)	(4,897		)
Long-term contract liabilities (included in Noncurrent contract liabilities)	(12,622		)	(14,611		)
Net contract liabilities	$	(24,543	)	$	(16,582	)

During the nine months ended September 30, 2019, the Company recognized $4.1 million of revenue upon satisfaction of performance obligations related to amounts that were included in the net contract liabilities balance as of December 31, 2018. The increase in the contract liabilities from December 31, 2018 to September 30, 2019 is primarily related to the prepayment for certain engines by a customer under a long-term supply agreement.

Remaining Performance Obligations

For performance obligations that extend beyond one year, the Company had $27.7 million of remaining performance obligations as of September 30, 2019. The Company expects to recognize revenue related to these remaining performance obligations of approximately $5.8 million in the remainder of 2019, $16.9 million in 2020, $2.9 million in 2021, $0.7 million in 2022, $0.6 million in 2023 and $0.8 million in 2024 and beyond.