Accumulated Other Comprehensive Loss Schedule of Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) before income taxes		$ 21,381	$ (11,564)	$ 184,146
Tax expense		6,911	(242)	61,501
Net income (loss)		14,470	(11,322)	122,645
Reclassification out of Accumulated Other Comprehensive Income
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	[1]	(347)	(40,532)	(339)
Amortization of prior-service cost | Reclassification out of Accumulated Other Comprehensive Income
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior-service cost	[1],[2]	(354)	(543)	(543)
Income (loss) before income taxes	[1]	(354)	(543)	(543)
Tax expense		133	204	204
Net income (loss)	[1]	(221)	(339)	$ (339)
Recognition of gain on sale of investment | Reclassification out of Accumulated Other Comprehensive Income
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Recognition of gain on sale of investment	[2],[3]	(200)
Income (loss) before income taxes	[3]	(200)
Tax expense		74
Net income (loss)	[3]	$ (126)
Settlement of defined benefit pension plan | Reclassification out of Accumulated Other Comprehensive Income
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior-service cost	[3]		64,939
Income (loss) before income taxes	[3]		(64,939)
Tax expense			24,746
Net income (loss)	[3]		$ (40,193)

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

[2] 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)

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