Shareholders' Equity Accumulated OCI Reclassified to Statement of Operations (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)		$ (58)	$ (59)	$ (138)
Other Amounts Recognized in Other Comprehensive Income, before tax		(4)	46	(68)
Income (loss) before income taxes		84,627	37,102	(18,265)
Income Tax Expense (Benefit)		(49,574)	(22,099)	(4,035)
Net income (loss)		35,053	15,003	(22,300)
Total reclassifications for the period, net of tax		35,053	15,003	(22,300)
Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	[1],[2]	(58)	(59)	(138)
Defined Benefit Plan, Amortization of Gains (Losses)	[1],[2]	(1,351)	(1,979)	(572)
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	[1],[2]	(1,343)	(375)	(55)
Other Amounts Recognized in Other Comprehensive Income, before tax	[1],[2]	0	(46)	0
Income (loss) before income taxes	[1]	(2,752)	(2,459)	(765)
Income Tax Expense (Benefit)	[1]	29	733	10
Net income (loss)	[1]	(2,723)	(1,726)	(755)
Total reclassifications for the period, net of tax	[1]	$ (2,723)	$ (1,726)	$ (755)

[1] Amounts in parenthesis indicate debits to the Consolidated Statements of Operations.

[2] These AOCI components are included in the computation of net periodic pension cost. Refer to Note 8 for additional details.