Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, at beginning of year	$ (17,330)		$ (24,400)
Net unrealized gains (losses) arising during the period	(2,770)		3,300
Less: Net realized gains reclassified to net income	(3,250)		(3,770)
Total other comprehensive income (loss)	480		7,070		$ (13,100)
Balance, at end of year	(16,850)		(17,330)		(24,400)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, after Tax	3,250		1,670		250
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	4,110		(650)		(730)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(6,880)		6,050		(12,620)
Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, Tax			300
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	1,200		1,300
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax	900		300
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax			1,900
Defined Benefit Plans
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, at beginning of year	(10,450)		(12,120)
Net unrealized gains (losses) arising during the period	0		1,000	[1]
Less: Net realized gains reclassified to net income	(3,250)	[2]	(670)	[3]
Balance, at end of year	(7,200)		(10,450)		(12,120)
Derivative Instruments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, at beginning of year	(3,170)		(2,520)
Net unrealized gains (losses) arising during the period	4,110	[4]	(3,750)	[1]
Less: Net realized gains reclassified to net income	0		(3,100)	[3]
Balance, at end of year	940		(3,170)		(2,520)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, at beginning of year	(3,710)		(9,760)
Net unrealized gains (losses) arising during the period	(6,880)		6,050
Less: Net realized gains reclassified to net income	0		0
Balance, at end of year	$ (10,590)		$ (3,710)		$ (9,760)

[1] Defined benefit plans, net of income tax of $0.3 million. See Note 14, "Employee Benefit Plans," for additional details. Derivative instruments, net of income tax expense of $1.3 million. See Note 11, "Derivative Instruments," for further details.

[2] Defined benefit plans, net of income tax of $0.9 million. See Note 14, "Employee Benefit Plans," for additional details

[3] Defined benefit plans, net of income tax of $0.3 million. See Note 14, "Employee Benefit Plans," for additional details. Derivative instruments, net of income tax expense of $1.9 million. See Note 11, "Derivative Instruments," for further details.

[4] Derivative instruments, net of income tax of $1.2 million. See Note 11, "Derivative Instruments," for further details.