Other Assets (Tables)

12 Months Ended

Dec. 31, 2017

Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]

Summary of Other Assets

	December 31,
	2016		2017
	(in thousands)
Restricted cash and cash equivalents	$	1,289	$	1,255
Pension asset		1,037		2,593
Other		950		995
Total	$	3,276	$	4,843