Equity - Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 469,577
Income tax expense	(185)	$ 630	$ (1,052)
Other comprehensive income (loss), net of tax	2,572	(1,332)	(4,424)
Ending balance	644,729	469,577
AOCI Attributable to Parent [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(28,024)	(26,692)	(22,268)
Gains (losses) arising during period	4,232	(2,231)	(3,432)
Amounts reclassified from accumulated other comprehensive loss	(1,475)	269	60
Income tax expense	(185)	630	(1,052)
Other comprehensive income (loss), net of tax	2,572	(1,332)	(4,424)
Ending balance	(28,159)	(28,024)	(26,692)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(21,814)	(20,149)	(22,268)
Gains (losses) arising during period	693	(2,231)	3,111
Amounts reclassified from accumulated other comprehensive loss	97	(64)	60
Income tax expense	(185)	630	(1,052)
Other comprehensive income (loss), net of tax	605	(1,665)	2,119
Ending balance	(23,916)	(21,814)	(20,149)
Accumulated Other-than-Temporary Impairment Attributable to Parent [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(6,210)	(6,543)
Gains (losses) arising during period			(6,543)
Amounts reclassified from accumulated other comprehensive loss	333	333
Other comprehensive income (loss), net of tax	333	333	(6,543)
Ending balance	(5,877)	$ (6,210)	$ (6,543)
Interest Rate Derivatives
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Gains (losses) arising during period	3,539
Amounts reclassified from accumulated other comprehensive loss	(1,905)
Other comprehensive income (loss), net of tax	1,634
Ending balance	1,634
ASU 2018-02 [Member] | AOCI Attributable to Parent [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Tax benefit or Translation adjustment related to adoption of ASU	(2,707)
ASU 2018-02 [Member] | Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Tax benefit or Translation adjustment related to adoption of ASU	$ (2,707)