Debt Obligations Debt Obligations (Details Textuals 2) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2013
Unsecured Debt [Member] \| $250.0M 5.400% Guaranteed Notes due 2014
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 250.0
Debt Instrument, Interest Rate, Stated Percentage	5.40%
Unsecured Debt [Member] \| $250.0M 7.500% Guaranteed Notes due 2015
Debt Instrument [Line Items]
Debt Instrument, Face Amount	250.0
Debt Instrument, Interest Rate, Stated Percentage	7.50%
Unsecured Debt [Member] \| $250.0M 6.000% Guaranteed Notes due 2016
Debt Instrument [Line Items]
Debt Instrument, Face Amount	250.0
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Unsecured Debt [Member] \| $300.0M 5.700% Guaranteed Notes due 2017
Debt Instrument [Line Items]
Debt Instrument, Face Amount	300.0
Debt Instrument, Interest Rate, Stated Percentage	5.70%
Unsecured Debt [Member] \| $325.0M 4.950% Guaranteed Notes due 2018
Debt Instrument [Line Items]
Debt Instrument, Face Amount	325.0
Debt Instrument, Interest Rate, Stated Percentage	4.95%
Unsecured Debt [Member] \| $250.0M 3.950% Guaranteed Notes due 2023
Debt Instrument [Line Items]
Debt Instrument, Face Amount	250.0
Debt Instrument, Interest Rate, Stated Percentage	3.95%
Unsecured Debt [Member] \| Three Year Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	150.0
Debt Instrument Term	3 years
Option to Extend Term Loan	1 year
Debt Instrument, Basis Spread on Variable Rate	1.75%
Unsecured Debt [Member] \| Four-Year Term Loan - Variable [Member]
Debt Instrument [Line Items]
Debt Instrument Term	4 years
Option to Extend Term Loan	1 year
Debt Instrument, Basis Spread on Variable Rate	1.75%
Unsecured Debt [Member] \| Three and Four Year Term Loan [Member]
Debt Instrument [Line Items]
Derivative, Lower Remaining Maturity Range	3 years
Derivative, Higher Remaining Maturity Range	4 years
Unsecured Debt [Member] \| Seven Year Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 200.0
Debt Instrument Term	7 years
Debt Instrument, Basis Spread on Variable Rate	1.90%
Senior notes 5.400 Percent due 2014 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.40%
Senior Notes Due2015 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	7.50%

Debt Instrument, Term

No definition available.

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- Definition

Option to Extend Term Loan

+ References

No definition available.

+ Details

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- Definition

The percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Balance Type:	na
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- Definition

The stated principal amount of the debt instrument at time of issuance, which may vary from the carrying amount because of unamortized premium or discount.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 21

-Paragraph 16, 20

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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

- Definition

Interest rate stated in the contractual debt agreement.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 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 210.5-02.22(a)(1))

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

+ Details

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Balance Type:	na
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- Details

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- Definition

High end period remaining until maturity for the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Low end period remaining until maturity of derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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