Accumulated Other Comprehensive Income (Loss) (Reclassifications Out of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) before income taxes		$ 53,156	$ (20,525)	$ 21,381
Income tax benefit		(11,931)	63,134	(6,911)
Net income (loss)		41,225	42,609	14,470
Reclassification out of Accumulated Other Comprehensive Income
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)		(514)	(347)	(347)
Reclassification out of Accumulated Other Comprehensive Income | Amortization of prior-service cost
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior-service cost	[1]	(910)	455	(354)
Income (loss) before income taxes		(910)	(455)	(354)
Income tax benefit		238	108	133
Net income (loss)		(672)	$ (347)	(221)
Reclassification out of Accumulated Other Comprehensive Income | Cash Flow Hedges
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) before income taxes		214
Income tax benefit		(56)
Net income (loss)		158
Interest payments		$ 214
Reclassification out of Accumulated Other Comprehensive Income | Recognition of gain on sale of investment
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior-service cost				200
Income (loss) before income taxes				(200)
Income tax benefit				74
Net income (loss)				$ (126)

[1] This accumulated other comprehensive income component is included in the computation of net periodic benefit cost (see Note 7. Employee Benefit Plans footnote for additional details)