Shareholders' Equity Reclassifications from Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reclassification Out Of Accumulated Other Comprehensive Income [Line Items]
Prior-service costs		$ (14)	$ (18)	$ (29)	$ (36)
Actuarial losses		(485)	(122)	(982)	(245)
Income (loss) before income taxes		(9,500)	27,692	1,428	26,921
Tax benefit (provision)		(3,966)	(7,848)	(9,529)	(7,195)
Net income (loss)		(13,466)	19,844	(8,101)	19,726
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Out Of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	[1]	(493)	(118)	(998)	(217)
Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Out Of Accumulated Other Comprehensive Income [Line Items]
Prior-service costs	[1],[2]	(14)	(18)	(29)	(36)
Actuarial losses	[1],[2]	(485)	(122)	(982)	(245)
Other	[1],[2]	0	(29)	0	(29)
Income (loss) before income taxes	[1]	(499)	(169)	(1,011)	(310)
Tax benefit (provision)	[1]	6	51	13	93
Net income (loss)	[1]	$ (493)	$ (118)	$ (998)	$ (217)

[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.