Revenue (Tables)

3 Months Ended

Mar. 31, 2019

Revenue.

Schedule of revenue by discipline

	Three months ended
	March 31,
	2019		2018
	(in thousands)
Ion Implant	$	57,092	$	85,475
Aftermarket		34,385		36,710
	$	91,477	$	122,185

Schedule of revenue by geographic markets

	Three months ended
	March 31,
	2019		2018
	(in thousands)
North America	$	11,607	$	10,523
Asia Pacific		62,927		97,689
Europe		16,943		13,973
	$	91,477	$	122,185

Schedule of contract assets and contract liabilities

	March 31,		December 31,
	2019		2018
	(in thousands)
Contract assets	$	—	$	—
Contract liabilities	$	20,481	$	22,584

Contract liabilities are reflected as deferred revenue on the consolidated balance sheet and relate to payments invoiced or received in advance of completion of performance obligations under a contract. Contract liabilities are recognized as revenue upon the fulfillment of performance obligations.

	Three months ended
	March 31,
	2019		2018
	(in thousands)
Revenue recognized in the period from:
Amounts included in contract liability at the beginning of the period	$	6,181	$	6,342
Performance obligations satisfied in previous periods	$	—	$	—