Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) (Schedule of Reclassifications) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
comprehensive income reclassifications [Line Items]
Revenues	$ 766,332	$ 965,685	$ 1,503,702	$ 1,925,922
Interest and investment income	1,216	1,088	4,052	2,109
Loss from continuing operations before income taxes	(129,819)	(693,575)	(273,488)	(739,529)
Benefit from income taxes	49,468	251,119	108,821	282,974
Net loss	(72,206)	(435,424)	(142,255)	(434,015)
reclassification out of accumulated other comprehensive income [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
comprehensive income reclassifications [Line Items]
Amortization of prior service credits			5,581
Amortization of actuarial gains (losses) net			(9,285)
Loss from continuing operations before income taxes			(3,704)
Benefit from income taxes			1,333
Net loss			(2,371)
reclassification out of accumulated other comprehensive income [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
comprehensive income reclassifications [Line Items]
Interest and investment income			(309)
Benefit from income taxes			111
Net loss			(198)
Commodity Contract [Member] | reclassification out of accumulated other comprehensive income [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
comprehensive income reclassifications [Line Items]
Revenues			1,401
Benefit from income taxes			(505)
Net loss			$ 896