Fair Value Measurements - Table 2 (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Advances under revolving credit facility	$ 10.0us-gaap_LineOfCredit	$ 325.0us-gaap_LineOfCredit
Term loan facilities	197.5us-gaap_LoansPayableToBank	450.0us-gaap_LoansPayableToBank
Other notes payable	41.1us-gaap_OtherNotesPayable	41.6us-gaap_OtherNotesPayable
Revolving Credit Facility [Member] \| Carrying Amount [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Advances under revolving credit facility	10.0	325.0
Revolving Credit Facility [Member] \| Estimated Fair Value [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Advances under revolving credit facility, Fair Value	10.0	325.0
Term Loan Facilities [Member] \| Carrying Amount [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Term loan facilities	197.5	450.0
Term Loan Facilities [Member] \| Estimated Fair Value [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Term loan facilities, Fair Value	197.5	450.0
8.125% Senior Notes Due 2020 [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Senior Notes	287.2	287.0
8.125% Senior Notes Due 2020 [Member] \| Carrying Amount [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Senior Notes	287.2	287.0
8.125% Senior Notes Due 2020 [Member] \| Estimated Fair Value [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Senior Notes, Fair Value	302.1	302.5
7.75% Senior Notes due 2022 [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Senior Notes	227.1	227.1
7.75% Senior Notes due 2022 [Member] \| Carrying Amount [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Senior Notes	227.1	227.1
7.75% Senior Notes due 2022 [Member] \| Estimated Fair Value [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Senior Notes, Fair Value	238.8	240.7
5.125% Senior Notes Due 2023 [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Senior Notes	300.0	0
5.125% Senior Notes Due 2023 [Member] \| Carrying Amount [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Senior Notes	300.0	0
5.125% Senior Notes Due 2023 [Member] \| Estimated Fair Value [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Senior Notes, Fair Value	305.6	0
5.75% Senior Notes Due 2024 [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Senior Notes	864.0	456.2
5.75% Senior Notes Due 2024 [Member] \| Carrying Amount [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Senior Notes	864.0	456.2
5.75% Senior Notes Due 2024 [Member] \| Estimated Fair Value [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Senior Notes, Fair Value	887.2	471.4
2.00% Convertible Senior Subordinated Notes due 2043 [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Convertible Subordinated Debt	260.2	258.0
2.00% Convertible Senior Subordinated Notes due 2043 [Member] \| Carrying Amount [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Convertible Subordinated Debt	260.2	258.0
2.00% Convertible Senior Subordinated Notes due 2043 [Member] \| Estimated Fair Value [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Convertible Debt, Fair Value	398.2	358.4
Other Notes Payable [Member] \| Carrying Amount [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Other notes payable	41.1	41.6
Other Notes Payable [Member] \| Estimated Fair Value [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Other Notes Payable, Fair Value	41.1	41.6
Letters of Credit [Member] \| Carrying Amount [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Letters of Credit	0	0
Letters of Credit [Member] \| Estimated Fair Value [Member]
Carrying Amounts and Estimated Fair Values, Financial Instruments [Abstract]
Letters of Credit, Fair Value	$ 35.4	$ 31.8

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Carrying amount of letters of credit at balance sheet date.

+ References

No definition available.

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- Definition

Fair value of other notes payable at the balance sheet date.

+ References

No definition available.

+ Details

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- Definition

Fair value portion of borrowing which can be exchanged for a specified number of another security at the option of the issuer or the holder, for example, but not limited to, the entity's common stock.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Convertible Security

-URI http://asc.fasb.org/extlink&oid=6509036

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- Definition

Including the current and noncurrent portions, the carrying value of convertible subordinated debt, as of the balance sheet date, initially scheduled to be repaid after one year or beyond the normal operating cycle if longer. This form of debt can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder, and places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX210.5-02.22))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Article 5

-Subsection 20, 22

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Data Type:	xbrli:monetaryItemType
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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of contractual arrangement with a lender under which borrowings can be made up to a specific amount at any point in time.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Line-of-Credit Arrangement

-URI http://asc.fasb.org/extlink&oid=6517033

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of contractual obligation to pay money on demand or on fixed or determinable dates.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of notes payable.

+ 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 Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19,20,22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Balance Type:	credit
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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

+ Details

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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

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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- Details

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- Details

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