v2.4.0.6

Acquisitions Purchase of Additional Interests (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
February 2012 [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Number of majority-owned subsidiaries	1
Acquisition of additional interests in majority-owned subsidiary	$ 2.5
Deferred compensation expense, service period, number of years	2 years 0 months 0 days
February 2012 [Member] | total settlement [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Stock-based compensation awards, settlement	2.5
February 2012 [Member] | total settlement, cash [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Stock-based compensation awards, settlement	2.4
February 2012 [Member] | total settlement, Class A common stock [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Stock-based compensation awards, settlement	0.5
February 2012 [Member] | total settlement, deferred compensation [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Stock-based compensation awards, settlement	1.7
February 2012 [Member] | compensation expense, cash [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Deferred compensation expense	1.3
February 2012 [Member] | compensation expense, Class A common stock [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Deferred compensation expense	0.4
May 2012 [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Number of majority-owned subsidiaries	2
Acquisition of additional interests in majority-owned subsidiary	6.6
May 2012 [Member] | Purchase of additional interests, Cash [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Acquisition of additional interests in majority-owned subsidiary	6.0
May 2012 [Member] | Purchase of additional interests, Stock [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Acquisition of additional interests in majority-owned subsidiary	$ 0.6

X

- Definition

Deferred compensation expense, service period, number of years

+ References

No definition available.

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X

- Definition

number of majority-owned subsidiaries

+ References

No definition available.

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X

- Definition

Stock-based compensation awards, settlement

+ References

No definition available.

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- Details

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X

- Definition

Represents the purchase by the parent of an additional equity interest in a subsidiary during the period, thereby effecting a change in total (consolidated) equity attributable to the parent. The purchase of the additional equity interest represented by this element increases the parent's controlling interest in the subsidiary.

+ References

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

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 38

-Subparagraph d

-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.



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 55

-Paragraph 4M

-URI http://asc.fasb.org/extlink&oid=18733213&loc=SL4591554-111686



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187085-122770



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

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph A7

-Appendix A

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X

- Definition

The compensation expense recognized during the period pertaining to the deferred compensation arrangement.

+ References

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 6, 7

-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.



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901



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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph 64, 65

-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.



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 710

-SubTopic 10

-Section 30

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20015-108363

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