Retirement Plans (Tables) - USD ($)
$ in Thousands

3 Months Ended

9 Months Ended

Sep. 30, 2017

Sep. 30, 2016

Sep. 30, 2017

Sep. 30, 2016

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Net Pension Income or Postretirement Expense

Net pension income for our domestic and foreign plans was as follows:

	Three Months Ended						Nine Months Ended
	September 30,			September 30,			September 30,			September 30,
	2017			2016			2017			2016
Net pension income	$	(492	)	$	(440	)	$	(1,416	)	$	(1,234	)

The components of net pension (income) expense for our domestic and foreign plans include the following: 

	DomesticPension Plans						Foreign Pension Plans
	Three Months Ended						Three Months Ended
	September 30,			September 30,			September 30,			September 30,
	2017			2016			2017			2016
Service cost	$	—		$	21		$	12		$	13
Interest cost	2,068			2,756			8			12
Expected return on plan assets (1)	(4,060		)	(4,744		)	(5		)	(33		)
Amortization of loss	1,446			1,499			39			36
(Income) expense, net	$	(546	)	$	(468	)	$	54		$	28

(1) Expected return on plan assets is net of expected investment expenses and certain administrative expenses.

	DomesticPension Plans						Foreign Pension Plans
	Nine Months Ended						Nine Months Ended
	September 30,			September 30,			September 30,			September 30,
	2017			2016			2017			2016
Service cost	$	—		$	65		$	36		$	38
Interest cost	6,204			8,268			25			34
Expected return on plan assets (1)	(12,181		)	(14,232		)	(15		)	(19		)
Amortization of loss	4,338			4,495			116			105
Other cost due to retirement	61			12			—			—
(Income) expense, net	$	(1,578	)	$	(1,392	)	$	162		$	158

(1) Expected return on plan assets is net of expected investment expenses and certain administrative expenses.

Net post-retirement expense for our other post-retirement plan includes the following components:

	Three Months Ended						Nine Months Ended
	September 30,			September 30,			September 30,			September 30,
	2017			2016			2017			2016
Service cost	$	—		$	—		$	1		$	2
Interest cost	41			52			121			156
Amortization of gain	(25		)	(37		)	(75		)	(112		)
Post-retirement expense	$	16		$	15		$	47		$	46

United States Pension Plan of US Entity [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Service cost

$ 0

$ 21

$ 0

$ 65