Long-Term Debt (Senior Unsecured Debt) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Dec. 31, 2013
Debt Instrument [Line Items]
Principal Outstanding	$ 8,125,773		$ 8,129,546
Senior Unsecured Debt [Member]
Debt Instrument [Line Items]
Principal Outstanding	8,092,691		8,107,066
Weighted average interest rate	7.79%	[1]	7.78%	[1]
Debt instrument, maturity date	Oct. 14, 2016
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member]
Debt Instrument [Line Items]
Principal Outstanding	7,842,691		7,857,066
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Senior Note Due 5/1/2014 [Member]
Debt Instrument [Line Items]
Principal Outstanding	200,000		200,000
Interest Rate	8.25%		8.25%
Debt instrument, maturity date	May 01, 2014
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Senior Note Due 3/15/2015 [Member]
Debt Instrument [Line Items]
Principal Outstanding	105,026		105,026
Interest Rate	6.625%		6.625%
Debt instrument, maturity date	Mar. 15, 2015
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Senior Note Due 4/15/2015 [Member]
Debt Instrument [Line Items]
Principal Outstanding	96,872		96,872
Interest Rate	7.875%		7.875%
Debt instrument, maturity date	Apr. 15, 2015
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Senior Note Due 10/14/2016 [Member]
Debt Instrument [Line Items]
Principal Outstanding	445,625	[2]	460,000	[2]
Interest Rate	3.035%	[2]	3.045%	[2]
Debt instrument, maturity date	Oct. 14, 2016	[2]
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Senior Note Due 4/15/2017 [Member]
Debt Instrument [Line Items]
Principal Outstanding	606,874		606,874
Interest Rate	8.25%		8.25%
Debt instrument, maturity date	Apr. 15, 2017
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Senior Note Due 10/1/2018 [Member]
Debt Instrument [Line Items]
Principal Outstanding	582,739		582,739
Interest Rate	8.125%		8.125%
Debt instrument, maturity date	Oct. 01, 2018
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Senior Note Due 3/15/2019 [Member]
Debt Instrument [Line Items]
Principal Outstanding	434,000		434,000
Interest Rate	7.125%		7.125%
Debt instrument, maturity date	Mar. 15, 2019
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Senior Note Due 4/15/2020 [Member]
Debt Instrument [Line Items]
Principal Outstanding	1,021,505		1,021,505
Interest Rate	8.50%		8.50%
Debt instrument, maturity date	Apr. 15, 2020
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Senior Note Due 7/1/2021 [Member]
Debt Instrument [Line Items]
Principal Outstanding	500,000		500,000
Interest Rate	9.25%		9.25%
Debt instrument, maturity date	Jul. 01, 2021
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Senior Note Due 4/15/2022 [Member]
Debt Instrument [Line Items]
Principal Outstanding	500,000		500,000
Interest Rate	8.75%		8.75%
Debt instrument, maturity date	Apr. 15, 2022
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Senior Note Due 1/15/2023 [Member]
Debt Instrument [Line Items]
Principal Outstanding	850,000		850,000
Interest Rate	7.125%		7.125%
Debt instrument, maturity date	Jan. 15, 2023
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Senior Note Due 4/15/2024 [Member]
Debt Instrument [Line Items]
Principal Outstanding	750,000		750,000
Interest Rate	7.625%		7.625%
Debt instrument, maturity date	Apr. 15, 2024
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Debenture Due 11/1/2025 [Member]
Debt Instrument [Line Items]
Principal Outstanding	138,000		138,000
Interest Rate	7.00%		7.00%
Debt instrument, maturity date	Nov. 01, 2025
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Debenture Due 8/15/2026 [Member]
Debt Instrument [Line Items]
Principal Outstanding	1,739		1,739
Interest Rate	6.80%		6.80%
Debt instrument, maturity date	Aug. 15, 2026
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Senior Note Due 1/15/2027 [Member]
Debt Instrument [Line Items]
Principal Outstanding	345,858		345,858
Interest Rate	7.875%		7.875%
Debt instrument, maturity date	Jan. 15, 2027
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Senior Note Due 8/15/2031 [Member]
Debt Instrument [Line Items]
Principal Outstanding	945,325		945,325
Interest Rate	9.00%		9.00%
Debt instrument, maturity date	Aug. 15, 2031
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Debenture Due 10/1/2034 [Member]
Debt Instrument [Line Items]
Principal Outstanding	628		628
Interest Rate	7.68%		7.68%
Debt instrument, maturity date	Oct. 01, 2034
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Debenture Due 7/1/2035 [Member]
Debt Instrument [Line Items]
Principal Outstanding	125,000		125,000
Interest Rate	7.45%		7.45%
Debt instrument, maturity date	Jul. 01, 2035
Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Debenture Due 10/1/2046 [Member]
Debt Instrument [Line Items]
Principal Outstanding	193,500		193,500
Interest Rate	7.05%		7.05%
Debt instrument, maturity date	Oct. 01, 2046
Subsidiary Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Subsidiary Senior Note Due 2/15/2028 [Member]
Debt Instrument [Line Items]
Principal Outstanding	200,000		200,000
Interest Rate	6.73%		6.73%
Debt instrument, maturity date	Feb. 15, 2028
Subsidiary Senior Notes And Debentures [Member] | Senior Unsecured Debt [Member] | Subsidiary Senior Note Due 10/15/2029 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 50,000		$ 50,000
Interest Rate	8.40%		8.40%
Debt instrument, maturity date	Oct. 15, 2029

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

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