Accumulated Other Comprehensive Income (Loss) (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Amounts reclassified out of each component of accumulated other comprehensive income (loss)
Interest expense	$ (53,129)	$ (31,104)	$ (105,747)	$ (59,171)
Other income (loss)	(714)	(5,919)	(609)	(12,912)
Income (loss) from continuing operations before income tax expense (benefit)	(84,252)	31,291	(199,735)	80,584
Income tax expense (benefit)	49,760	(4,535)	115,799	(13,212)
Net income (loss)	(34,492)	31,936	(83,936)	72,552
Amount Reclassified from Accumulated Other Comprehensive Income (Loss)
Amounts reclassified out of each component of accumulated other comprehensive income (loss)
Net income (loss)			8,091
Gains and losses on cash flow hedges | Amount Reclassified from Accumulated Other Comprehensive Income (Loss)
Amounts reclassified out of each component of accumulated other comprehensive income (loss)
Income (loss) from continuing operations before income tax expense (benefit)			(1,991)
Income tax expense (benefit)			(761)
Net income (loss)			(1,230)
Gains and losses on cash flow hedges | Amount Reclassified from Accumulated Other Comprehensive Income (Loss) | Interest rate swaps
Amounts reclassified out of each component of accumulated other comprehensive income (loss)
Interest expense			(1,991)
Amortization of pension and postretirement benefit plans | Amount Reclassified from Accumulated Other Comprehensive Income (Loss)
Amounts reclassified out of each component of accumulated other comprehensive income (loss)
Prior service cost			746
Net actuarial loss			14,336
Income (loss) from continuing operations before income tax expense (benefit)			15,082
Income tax expense (benefit)			5,765
Net income (loss)			9,317
Gains and losses on available-for-sale securities | Amount Reclassified from Accumulated Other Comprehensive Income (Loss)
Amounts reclassified out of each component of accumulated other comprehensive income (loss)
Other income (loss)			4
Income (loss) from continuing operations before income tax expense (benefit)			4
Net income (loss)			$ 4