Accumulated Other Comprehensive Loss - Summary of Changes in Accumulated Other Comprehensive Loss by Component (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			$ 469,577				$ 469,577
Other Comprehensive Income (Loss), Net of Tax	$ (7,593)	$ 98	109	$ 3,439	$ 84	$ 78
Tax benefit and Translation adjustment related to adoption of ASU						(134)
Ending balance	311,478						311,478
Interest Rate Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Losses (gains) arising during period							(3,789)
Amounts reclassified from accumulated other comprehensive loss							(1,197)
Net other comprehensive income							(4,986)
Ending balance	(4,986)						(4,986)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(21,814)			(20,149)	(21,814)	$ (20,149)
Losses (gains) arising during period							(5,164)	3,439
Amounts reclassified from accumulated other comprehensive loss							1,635	990
Income tax benefit							(880)	1,077
Net other comprehensive income							(2,649)	3,352
Tax benefit and Translation adjustment related to adoption of ASU	(2,707)						(2,707)
Ending balance	(27,170)			(16,797)			(27,170)	(16,797)
Accumulated Other-than-Temporary Impairment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(6,210)			(6,543)	(6,210)	(6,543)
Amounts reclassified from accumulated other comprehensive loss							249	249
Net other comprehensive income							249	249
Ending balance	(5,961)			(6,294)			(5,961)	(6,294)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(28,024)			(26,692)	(28,024)	(26,692)
Losses (gains) arising during period							(8,953)	3,439
Amounts reclassified from accumulated other comprehensive loss							687	1,239
Income tax benefit							(880)	1,077
Net other comprehensive income							(7,386)	3,601
Other Comprehensive Income (Loss), Net of Tax	(7,593)	$ 98	$ 109	3,439	$ 84	$ 78
Tax benefit and Translation adjustment related to adoption of ASU	(2,707)						(2,707)
Ending balance	$ (38,117)			$ (23,091)			$ (38,117)	$ (23,091)