Accumulated Other Comprehensive Income (Loss) (Schedule of Reclassifications) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Revenues	$ 563,249	$ 688,544	$ 644,462	$ 677,005	$ 745,192	$ 742,180	$ 713,776	$ 735,971	$ 2,573,260	$ 2,937,119	$ 3,014,357
Loss from continuing operations before income taxes									(3,286,522)	(532,719)	(1,080,726)
Provision for (benefit from) income taxes									373,380	(25,634)	335,498
Net loss	$ (632,368)	$ (1,999,476)	$ (168,103)	$ (113,195)	$ (240,135)	$ (97,218)	$ (96,860)	$ (124,140)	(2,913,142)	(558,353)	$ (641,832)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax									(3,097)	9,885
Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax									6,128	1,692
Pension, Postretirement and Other Post-Employment Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax									(5,142)	5,736
Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax									(4,083)	2,457
Reclassification out of accumulated other comprehensive income [Member] | Derivative Instruments [Member] | Commodity Contract [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Revenues									9,575	2,643
Provision for (benefit from) income taxes									(3,447)	(951)
Net loss									6,128	1,692
Reclassification out of accumulated other comprehensive income [Member] | Pension, Postretirement and Other Post-Employment Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of prior service credits									8,335	11,760
Amortization of net actuarial gains (losses)									(16,369)	(2,797)
Loss from continuing operations before income taxes									(8,034)	8,963
Provision for (benefit from) income taxes									2,892	(3,227)
Net loss									(5,142)	5,736
Reclassification out of accumulated other comprehensive income [Member] | Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and investment income									(6,391)	3,838
Provision for (benefit from) income taxes									2,308	(1,381)
Net loss									$ (4,083)	$ 2,457