Accumulated Other Comprehensive Loss Schedule of Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) before income taxes		$ (11,564)	$ 184,146	$ 149,513
Income tax benefit		(242)	61,501	53,811
Net income (loss)		(11,322)	122,645	95,702
Reclassification out of Accumulated Other Comprehensive Income
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	[1]	(40,532)	(339)	(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]	(543)	(543)	(543)
Income (loss) before income taxes	[1]	(543)	(543)	(543)
Income tax benefit	[1]	204	204	204
Net income (loss)	[1]	(339)	$ (339)	$ (339)
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)
Income tax benefit	[3]	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