Other Comprehensive Income Reclassifications from Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Reclassification Out Of Accumulated Other Comprehensive Income [Line Items]
Prior-service costs	$ (18)		$ (17)		$ (36)		$ (34)
Actuarial losses	122		246		245		497
Total, before tax	27,692		14,092		26,921		14,345
Tax benefit (provision)	(7,848)		(1,896)		(7,195)		1,347
Total, net of tax	19,844		12,196		19,726		15,692
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Out Of Accumulated Other Comprehensive Income [Line Items]
Total, net of tax	(118)	[1]	(183)	[1]	(217)	[1]	(369)	[1]
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	(18)	[1],[2]	(17)	[1],[2]	(36)	[1],[2]	(34)	[1],[2]
Actuarial losses	(122)	[1],[2]	(246)	[1],[2]	(245)	[1],[2]	(497)	[1],[2]
Other	(29)	[1],[2]	0	[1],[2]	(29)	[1],[2]	0	[1],[2]
Total, before tax	(169)	[1]	(263)	[1]	(310)	[1]	(531)	[1]
Tax benefit (provision)	51	[1]	80	[1]	93	[1]	162	[1]
Total, net of tax	$ (118)	[1]	$ (183)	[1]	$ (217)	[1]	$ (369)	[1]

[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.