Fair Value Measurements (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013 interest_rate_swaps	Dec. 31, 2012
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Fair value interest rate swap discount rate	1.60%
Number of interest rate swaps to convert fixed interest rate on notes to floating rate	2
Assets or liabilities transferred between Level 1 and Level 2	$ 0
Assets or liabilities transferred between Level 2 and Level 3	0
Net addition to the fair value of liabilities for prior period acquisitions	1
Percent change in projections affecting fair value of contigent consideration	5.00%
Increase in fair value of contingent consideration due to 5% increase in projections	28
Decrease in fair value of contigent considertion due to 5% decrease in projections	15
Available-for-sale Securities, Amortized Cost Basis	16	16
Minimum [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Revenue target period (in years)	2 years
Maximum [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Revenue target period (in years)	4 years
Senior Debt Obligations Due 2014 [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Fair value interest rate swap derivatives	$ 250

Decrease in Fair Value of Contigent Considertion Due to 5% Decrease in Projections

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- Definition

Fair Value Interest Rate Discount Rate

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- Definition

Fair Value, Level 1 To Level 2 Transfers Assets or Labilities, Amount

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Fair Value, Level 2 To Level 3 Transfers Assets or Labilities, Amount

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Increase in Fair Value of Contingent Consideration Due to 5% Increase in Projections

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- Definition

Number of interest rate swaps to convert fixed interest rate on notes to floating rate

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Percent Change in Projections Affecting Fair Value of Contigent Consideration

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Revenue target period.

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- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.2)

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-Publisher FASB

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- Definition

This element represents the amount of any change, including any differences arising upon settlement, recognized during the reporting period in the value of a liability, arising from an item of contingent consideration, assumed in a business combination.

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

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-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 50

-Paragraph 4

-Subparagraph (a)(1)

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-Name Statement of Financial Accounting Standard (FAS)

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- Definition

Fair value as of the balance sheet date of interest rate derivative assets, net of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized on the balance sheet.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

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-Paragraph 10

-Subparagraph (a)

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