Retirement Plans (Tables)

6 Months Ended

Jun. 30, 2017

Defined Benefit Plan Disclosure [Line Items]

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,
	2017		2016		2017		2016
United States	$	410	$	445	$	861	$	1,137
Canada	54		67		113		118
United Kingdom	98		160		213		218
	$	562	$	672	$	1,187	$	1,473

United States Plan

Defined Benefit Plan Disclosure [Line Items]

Schedule of Net Benefit Costs

Net periodic pension costs for the United States defined benefit pension plans for the three- and six-month periods ended June 30, 2017 and 2016 are as follows:

	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
Service cost	$	—		$	9		$	—		$	18
Interest cost	171			186			342			372
Expected return on plan assets	(178		)	(179		)	(355		)	(358		)
Recognized net actuarial loss	33			69			65			138
Net periodic pension cost	$	26		$	85		$	52		$	170

United Kingdom Benefit Plans

Defined Benefit Plan Disclosure [Line Items]

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, 2017 and 2016 are as follows:

	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
Interest cost	$	55		$	75		$	110		$	150
Expected return on plan assets	(66		)	(84		)	(132		)	(168		)
Amortization of prior service costs and transition amount	4			5			8			10
Recognized net actuarial loss	71			39			142			78
Net periodic pension cost	$	64		$	35		$	128		$	70