Long-Term Debt (Details) (USD $)	3 Months Ended			6 Months Ended				12 Months Ended		12 Months Ended		6 Months Ended									0 Months Ended	1 Months Ended	6 Months Ended								6 Months Ended																																																			6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012	Jun. 30, 2013		Jun. 30, 2012	Dec. 31, 2012	Dec. 31, 2011 Unsecured Letter of Credit Facility [Member]	Dec. 31, 2012 Unsecured Letter of Credit Facility [Member] LetterofCredit	Dec. 31, 2012 Unsecured Letter of Credit Facility [Member] March 2013 [Member]	Dec. 31, 2012 Unsecured Letter of Credit Facility [Member] September 2013 [Member]	Jun. 30, 2013 Revolving Credit Facility [Member]	Apr. 24, 2013 Senior Note Due 3/15/2015 [Member]	Apr. 10, 2013 Senior Note Due 3/15/2015 [Member]	Apr. 24, 2013 Senior Note Due 4/15/2015 [Member]	Apr. 10, 2013 Senior Note Due 4/15/2015 [Member]	Jun. 30, 2013 Senior Note Due 4/15/2017 [Member]	Apr. 24, 2013 Senior Note Due 4/15/2017 [Member]	Jun. 30, 2013 Senior Note Due 10/1/2018 [Member]	Jun. 30, 2013 Senior Note Due 4/15/2020 [Member]	Apr. 10, 2013 Senior Notes Due 2024 [Member]	Apr. 24, 2013 Senior Note [Member]	Jun. 30, 2013 Senior Note [Member]	Apr. 10, 2013 Senior Note [Member]	Jun. 30, 2013 Senior Notes and Debentures [Member]		Dec. 31, 2012 Senior Notes and Debentures [Member]		Jun. 30, 2013 Senior Notes and Debentures [Member] Senior Notes Due 2024 [Member]	Dec. 31, 2012 Senior Notes and Debentures [Member] Senior Notes Due 2024 [Member]	Jun. 30, 2013 Senior Unsecured Term Loan [Member]	Jun. 30, 2013 Rural Utilities Service Loan Contracts [Member]		Jun. 30, 2013 Senior Unsecured Debt [Member]		Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Note Due 2/15/2028 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Note Due 2/15/2028 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Note Due 10/15/2029 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Note Due 10/15/2029 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 1/15/2013 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 1/15/2013 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 5/1/2014 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 5/1/2014 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 3/15/2015 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 3/15/2015 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 4/15/2015 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 4/15/2015 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 4/15/2017 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 4/15/2017 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 10/1/2018 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 10/1/2018 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 1/15/2023 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 1/15/2023 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 3/15/2019 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 3/15/2019 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 4/15/2020 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 4/15/2020 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 7/1/2021 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 7/1/2021 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 4/15/2022 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 4/15/2022 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 1/15/2027 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 1/15/2027 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 8/15/2031 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 8/15/2031 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Debenture Due 11/1/2025 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Debenture Due 11/1/2025 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Debenture Due 8/15/2026 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Debenture Due 8/15/2026 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Debenture Due 10/1/2034 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Debenture Due 10/1/2034 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Debenture Due 7/1/2035 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Debenture Due 7/1/2035 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Debenture Due 10/1/2046 [Member]	Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Debenture Due 10/1/2046 [Member]	Jun. 30, 2013 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 10/14/2016 [Member]		Dec. 31, 2012 Senior Unsecured Debt [Member] Senior Notes and Debentures [Member] Senior Note Due 10/14/2016 [Member]		Jun. 30, 2013 Industrial Development Revenue Bonds [Member]
Long Term Debt [Roll Forward]
Long-term debt, beginning balance				$ 8,942,568,000																									$ 750,000,000	$ 0		$ 9,322,000		$ 8,919,696,000		$ 200,000,000	$ 200,000,000	$ 50,000,000	$ 50,000,000	$ 7,885,816,000	$ 8,669,696,000	$ 0	$ 502,658,000	$ 200,000,000	$ 200,000,000	$ 105,026,000	$ 300,000,000	$ 96,872,000	$ 374,803,000	$ 606,874,000	$ 1,040,685,000	$ 582,739,000	$ 600,000,000	$ 850,000,000	$ 850,000,000	$ 434,000,000	$ 434,000,000	$ 1,021,505,000	$ 1,100,000,000	$ 500,000,000	$ 500,000,000	$ 500,000,000	$ 500,000,000	$ 345,858,000	$ 345,858,000	$ 945,325,000	$ 945,325,000	$ 138,000,000	$ 138,000,000	$ 1,739,000	$ 1,739,000	$ 628,000	$ 628,000	$ 125,000,000	$ 125,000,000	$ 193,500,000	$ 193,500,000	$ 488,750,000	[1]	$ 517,500,000	[1]	$ 13,550,000
Payments and Retirements				(1,534,074,000)																												(194,000)		(1,533,880,000)																																																0
New Borrowings				750,000,000																												0		750,000,000																																																0
Long-term debt, ending balance	8,158,494,000			8,158,494,000																									750,000,000	0		9,128,000		8,135,816,000		200,000,000	200,000,000	50,000,000	50,000,000	7,885,816,000	8,669,696,000	0	502,658,000	200,000,000	200,000,000	105,026,000	300,000,000	96,872,000	374,803,000	606,874,000	1,040,685,000	582,739,000	600,000,000	850,000,000	850,000,000	434,000,000	434,000,000	1,021,505,000	1,100,000,000	500,000,000	500,000,000	500,000,000	500,000,000	345,858,000	345,858,000	945,325,000	945,325,000	138,000,000	138,000,000	1,739,000	1,739,000	628,000	628,000	125,000,000	125,000,000	193,500,000	193,500,000	488,750,000	[1]	517,500,000	[1]	13,550,000
Less: Debt (Discount)/Premium	333,000			333,000			(71,000)
Less: Current Portion	(257,905,000)			(257,905,000)			(560,550,000)
Principal Outstanding	7,900,922,000			7,900,922,000			8,381,947,000
Senior Notes [Abstract]
Principal Outstanding	8,158,494,000			8,158,494,000																									750,000,000	0		9,128,000		8,135,816,000		200,000,000	200,000,000	50,000,000	50,000,000	7,885,816,000	8,669,696,000	0	502,658,000	200,000,000	200,000,000	105,026,000	300,000,000	96,872,000	374,803,000	606,874,000	1,040,685,000	582,739,000	600,000,000	850,000,000	850,000,000	434,000,000	434,000,000	1,021,505,000	1,100,000,000	500,000,000	500,000,000	500,000,000	500,000,000	345,858,000	345,858,000	945,325,000	945,325,000	138,000,000	138,000,000	1,739,000	1,739,000	628,000	628,000	125,000,000	125,000,000	193,500,000	193,500,000	488,750,000	[1]	517,500,000	[1]	13,550,000
Interest Rate (in hundredths)																													7.625%	0.00%						6.73%	6.73%	8.40%	8.40%			0.00%	6.25%	8.25%	8.25%	6.625%	6.625%	7.875%	7.875%	8.25%	8.25%	8.125%	8.125%	7.125%	7.125%	7.125%	7.125%	8.50%	8.50%	9.25%	9.25%	8.75%	8.75%	7.875%	7.875%	9.00%	9.00%	7.00%	7.00%	6.80%	6.80%	7.68%	7.68%	7.45%	7.45%	7.05%	7.05%	3.075%	[1]	3.095%	[1]
Weighted average interest rate (in hundredths)	7.95%	[2]		7.95%	[2]																				7.77%	[3]	7.69%	[3]				6.15%	[2]	7.96%	[2]																																															6.33%	[2]
Credit Agreement [Abstract]
Issue price expressed as a percentage of principal amount (in hundredths)																					100.00%
Repayment of the outstanding principal balance, quarterly installments amount																															14,400,000
Proceeds from debt, net of issuance costs																					736,900,000
Amount of consideration for purchase of notes													800,000	216,000,000	900,000	316,400,000		267,700,000						532,400,000
Aggregate principal amount agreed to be purchased													700,000	194,200,000	800,000	277,100,000		225,000,000						471,300,000
Loss on early extinguishment of debt	(159,780,000)		(70,818,000)	(159,780,000)		(70,818,000)																(104,900,000)	(54,900,000)
Loss on early extinguishment of debt, net of tax																						(64,900,000)	(34,000,000)
Loss on early extinguishment of debt, net of tax (in dollars per share)																						$ (0.06)	$ (0.04)
Repurchase of senior notes																	208,800,000		17,300,000	78,500,000
Debt instrument, face amount																															575,000,000
Debt instrument, maturity date																															Oct. 14, 2016
Interest rate margin for Base Rate borrowings, minimum (in hundredths)																															0.875%
Interest rate margin for Base Rate borrowings, maximum (in hundredths)																															2.875%
Interest rate margin for LIBOR borrowings, minimum (in hundredths)																															1.875%
Interest rate margin for LIBOR borrowings, maximum (in hundredths)																															3.875%
Initial pricing for LIBOR based borrowings (in hundredths)																															2.875%
Maximum permitted leverage ratio																															4.5
Credit facilities [Abstract]
Line of credit facility maximum borrowing capacity								190,000,000	40,000,000	20,000,000	20,000,000	750,000,000
Interest Rate (in hundredths)												0.40%
Line of credit facility expiration date								Sep. 30, 2011		Mar. 31, 2013	Sep. 30, 2013	Nov. 03, 2016
Exercised extension of commitment									100,000,000
Number of letters of credit									2
Principal payments by year [Abstract]
Principal Payments 2013 (remaining six months)	28,948,000			28,948,000
Principal Payments 2014	257,916,000			257,916,000
Principal Payments 2015	259,840,000			259,840,000
Principal Payments 2016	345,466,000			345,466,000
Principal Payments 2017	607,375,000			607,375,000
Principal Payments 2018	$ 583,273,000			$ 583,273,000

[1] Represents borrowings under the Credit Agreement with CoBank.

[2] Interest rate includes amortization of debt issuance costs and debt premiums or discounts. The interest rates at March 31, 2013 represent a weighted average of multiple issuances.

[3] Interest rate represents a weighted average of the stated interest rates of multiple issuances.