Fair Value Measurements (Details 2) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Carrying amounts and estimated fair values for all other financial instruments:
Advances under $500 million revolving credit facility	$ 140.0	$ 78.0
Term Loan Facility	100.0	0
Other Notes Payable	36.1	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	164.0	495.5
10.75% Senior Notes due 2016 [Member] \| Estimate of Fair Value [Member]
Carrying amounts and estimated fair values for all other financial instruments:
Bonds payable	174.9	543.2
7.25% Senior Notes due 2018 \| 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 \| Estimate of Fair Value [Member]
Carrying amounts and estimated fair values for all other financial instruments:
Bonds payable	350.1	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	285.6	285.5
8.125% Senior Notes due 2020 [Member] \| Estimate of Fair Value [Member]
Carrying amounts and estimated fair values for all other financial instruments:
Bonds payable	311.0	311.8
7.75% Senior Notes due 2022 \| 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 \| Estimate of Fair Value [Member]
Carrying amounts and estimated fair values for all other financial instruments:
Bonds payable	327.8	258.1
Other bonds payable [Member] \| Carrying Amount [Member]
Carrying amounts and estimated fair values for all other financial instruments:
Bonds Payable	1.8	1.8
Other bonds payable [Member] \| Estimate of Fair Value [Member]
Carrying amounts and estimated fair values for all other financial instruments:
Bonds payable	1.8	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	140.0	78.0
Term Loan Facility	100.0	0
Other Notes Payable	36.1	36.4
Letters of credit	0	0
Estimate of 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	140.0	78.0
Term Loan Facility	100.0	0
Other notes payable	36.1	36.4
Letters of credit	$ 48.1	$ 45.6

Carrying Amounts And Estimated Fair Value Other Financial Instruments .

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Carrying amount of letters of credit at balance sheet date.

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Fair value of letters of credit at balance sheet date.

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Fair value of other notes payable at balance sheet date.

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 4, 17

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 10

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 3
-Section A
-Paragraph 4

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FIN39-1
-Paragraph 10A, 10B

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Fair value of derivative asset, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 205G

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44C
-Subparagraph a
-Clause 1

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Fair value of derivative liability, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

+ References

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 3
-Section A
-Paragraph 7

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
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-Paragraph 10A, 10B

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 4, 17

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 20, 22
-Article 5

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. Fair value of lines of credit at the balance sheet date.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of loans from a bank with maturities initially due after one year or beyond the normal operating cycle if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 20, 22
-Article 5

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents notes payable as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 20, 22
-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 129
-Paragraph 2, 4

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- Definition

Including the current and noncurrent portions, the carrying value of notes payable which were initially due after one year or beyond the normal operating cycle, if longer, and which are not otherwise defined in the taxonomy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 20, 22
-Article 5

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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 16
-Article 9

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