Retirement Plans (Tables)

6 Months Ended

Jun. 30, 2018

Defined Benefit Plan Disclosure

Schedule of Costs of Retirement Plans

The following table summarizes the expense associated with the contributions made to these plans:

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
United States	$	770	$	410	$	1,314	$	861
Canada	34		54		68		113
United Kingdom	98		98		214		213
	$	902	$	562	$	1,596	$	1,187

Pension Plan | United States

Defined Benefit Plan Disclosure

Schedule of Net Benefit Costs

Net periodic pension costs for the United States defined benefit pension plan for the three- and six-month periods ended June 30, 2018 and 2017 are as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
Interest cost	$	155	$	171	$	311	$	342
Expected return on plan assets	(213)		(178)		(427)		(355)
Recognized net actuarial loss	24		33		48		65
Net periodic pension (income) cost	$	(34)	$	26	$	(68)	$	52

Pension Plan | Foreign Plan

Defined Benefit Plan Disclosure

Schedule of Net Benefit Costs

Net periodic pension costs for the United Kingdom defined benefit pension plan for the three- and six-month periods ended June 30, 2018 and 2017 are as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
Interest cost	$	52	$	55	$	104	$	110
Expected return on plan assets	(71)		(66)		(142)		(132)
Amortization of prior service costs and transition amount	5		4		10		8
Recognized net actuarial loss	49		71		98		142
Net periodic pension cost	$	35	$	64	$	70	$	128