Supplemental Balance Sheet, Income Statement and Cash Flow Information (Details 4) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Supplemental Balance Sheet, Income Statement and Cash Flow Information
Losses (gains) on sales, disposals and involuntary conversions of long-lived assets	$ (27,641,000)	$ 2,806,000	$ (14,095,000)	$ 8,150,000
Litigation expenses	3,177,000	1,983,000	6,804,000	7,642,000
Merger transaction expenses	17,000,000		17,000,000
Foreign currency transaction losses (gains)	2,374,000	(290,000)	3,417,000	7,017,000
Other losses (gains)	3,577,000	(1,233,000)	3,341,000	4,436,000
Losses (gains) on sales and retirements of long-lived assets and other expense (income), net	(1,513,000)	3,266,000	16,467,000	27,245,000
Gain on disposition of our Alaska E&P assets	22,200,000
Termination of employment contract				45,000,000
Loss on tendered notes		208,197,000		208,197,000
Provision for retirement of assets		14,044,000		14,044,000
Impairment of long-lived assets		20,000,000		20,000,000
Total impairments and other charges	0	242,241,000	0	287,241,000
Accumulated other comprehensive income (loss)
Balance at the beginning of the period			216,140,000	340,143,000
Other comprehensive income (loss) before reclassifications, net of tax			(80,698,000)	(35,304,000)
Amount reclassified from accumulated other comprehensive income (loss)			(3,220,000)	(84,660,000)
Other comprehensive income (loss), net of tax	(56,331,000)	12,615,000	(83,918,000)	(119,964,000)
Balance at the end of the period	132,222,000	220,179,000	132,222,000	220,179,000
Gains (losses) on cash flow hedges
Accumulated other comprehensive income (loss)
Balance at the beginning of the period			(2,419,000)	(2,793,000)
Amount reclassified from accumulated other comprehensive income (loss)			280,000	280,000
Other comprehensive income (loss), net of tax			280,000	280,000
Balance at the end of the period	(2,139,000)	(2,513,000)	(2,139,000)	(2,513,000)
Unrealized gains (losses) on available-for-sale securities
Accumulated other comprehensive income (loss)
Balance at the beginning of the period			71,742,000	134,229,000
Other comprehensive income (loss) before reclassifications, net of tax			(34,646,000)	1,549,000
Amount reclassified from accumulated other comprehensive income (loss)			(3,726,000)	(85,456,000)
Other comprehensive income (loss), net of tax			(38,372,000)	(83,907,000)
Balance at the end of the period	33,370,000	50,322,000	33,370,000	50,322,000
Defined benefit pension plan items
Accumulated other comprehensive income (loss)
Balance at the beginning of the period			(4,075,000)	(7,632,000)
Amount reclassified from accumulated other comprehensive income (loss)			226,000	516,000
Other comprehensive income (loss), net of tax			226,000	516,000
Balance at the end of the period	(3,849,000)	(7,116,000)	(3,849,000)	(7,116,000)
Foreign currency items
Accumulated other comprehensive income (loss)
Balance at the beginning of the period			150,892,000	216,339,000
Other comprehensive income (loss) before reclassifications, net of tax			(46,052,000)	(36,853,000)
Other comprehensive income (loss), net of tax			(46,052,000)	(36,853,000)
Balance at the end of the period	$ 104,840,000	$ 179,486,000	$ 104,840,000	$ 179,486,000