Fair Value Measurements (Details 1) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Carrying amounts and estimated fair values for all other financial instruments:
Advances under $500 million revolving credit facility	$ 178.0	$ 78.0
Term Loan Facility	98.8	0
Other Notes Payable	35.9	36.4
10.75% Senior Notes due 2016 [Member] \| Carrying Amount [Member]
Carrying amounts and estimated fair values for all other financial instruments:
Bonds Payable	0	495.5
10.75% Senior Notes due 2016 [Member] \| Estimated Fair Value [Member]
Carrying amounts and estimated fair values for all other financial instruments:
Bonds payable	0	543.2
7.25% Senior Notes due 2018 [Member] \| Carrying Amount [Member]
Carrying amounts and estimated fair values for all other financial instruments:
Bonds Payable	336.8	275.0
7.25% Senior Notes due 2018 [Member] \| Estimated Fair Value [Member]
Carrying amounts and estimated fair values for all other financial instruments:
Bonds payable	321.2	280.5
8.125% Senior Notes due 2020 [Member] \| Carrying Amount [Member]
Carrying amounts and estimated fair values for all other financial instruments:
Bonds Payable	285.7	285.5
8.125% Senior Notes due 2020 [Member] \| Estimated Fair Value [Member]
Carrying amounts and estimated fair values for all other financial instruments:
Bonds payable	276.2	311.8
7.75% Senior Notes due 2022 [Member] \| Carrying Amount [Member]
Carrying amounts and estimated fair values for all other financial instruments:
Bonds Payable	312.0	250.0
7.75% Senior Notes due 2022 [Member] \| Estimated Fair Value [Member]
Carrying amounts and estimated fair values for all other financial instruments:
Bonds payable	280.6	258.1
Other Bonds Payable [Member] \| Carrying Amount [Member]
Carrying amounts and estimated fair values for all other financial instruments:
Bonds Payable	1.5	1.8
Other Bonds Payable [Member] \| Estimated Fair Value [Member]
Carrying amounts and estimated fair values for all other financial instruments:
Bonds payable	1.5	1.8
Carrying Amount [Member]
Carrying amounts and estimated fair values for all other financial instruments:
March 2006 trading swap	0	(12.1)
June 2009 trading swap	0	1.2
Advances under $500 million revolving credit facility	178.0	78.0
Term Loan Facility	98.8	0
Other Notes Payable	35.9	36.4
Letters of credit	0	0
Estimated Fair Value [Member]
Carrying amounts and estimated fair values for all other financial instruments:
March 2006 trading swap	0	(12.1)
June 2009 trading swap	0	1.2
Advances under $500 million revolving credit facility	178.0	78.0
Term Loan Facility	98.8	0
Other notes payable	35.9	36.4
Letters of credit	$ 46.0	$ 45.6

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Fair values as of the balance sheet date for all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments and which are expected to be converted into cash or otherwise disposed of within a year or the normal operating cycle, if longer, net of the effects of master netting arrangements.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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