Accumulated Other Comprehensive Loss - Schedule of Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) before income taxes		$ (19,065)	$ 23,109	$ (24,635)	$ 201
Income tax provision (benefit)		7,652	7,668	5,117	382
Net income (loss)		(26,717)	15,441	$ (29,752)	(181)
Reclassification out of Accumulated Other Comprehensive Income
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	[1]		(56)		(238)
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior-service cost	[2],[3]		(89)		(177)
Income (loss) before income taxes			(89)		(177)	[2]
Income tax provision (benefit)			33		65
Net income (loss)			$ (56)		(112)	[2]
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Recognition of gain on sale of investment		0			(200)	[1]
Income (loss) before income taxes		0			(200)	[1]
Income tax provision (benefit)		0			74
Net income (loss)		$ 0			$ (126)	[1]

[1] Amounts in parentheses indicate credits to profit/loss

[2] All amounts are net of tax. Amounts in parentheses indicate debits

[3] This accumulated other comprehensive loss component is included in the computation of net periodic benefit cost (see Note 6).