Accumulated Other Comprehensive Income (Loss) (Schedule of Reclassifications) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Revenues	$ 791,269	$ 975,170	$ 2,294,971	$ 2,901,092
Loss from continuing operations before income taxes	(329,680)	44,991	(603,168)	(694,538)
Provision for (benefit from) income taxes	121,913	(20,318)	230,734	262,656
Net income (loss)	(128,363)	45,751	(270,618)	(388,264)
reclassification out of accumulated other comprehensive income [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of prior service credits	5,573		11,154
Amortization of actuarial gains (losses), net	(3,823)		(13,108)
Loss from continuing operations before income taxes	1,750		(1,954)
Provision for (benefit from) income taxes	(631)		702
Net income (loss)	1,119		(1,252)
reclassification out of accumulated other comprehensive income [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and investment income	(4)		(313)
Provision for (benefit from) income taxes	2		113
Net income (loss)	(2)		(200)
Commodity Contract [Member] | reclassification out of accumulated other comprehensive income [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Revenues	692		2,093
Provision for (benefit from) income taxes	(249)		(754)
Net income (loss)	$ 443		$ 1,339