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Fair Value Measurements (Details) - USD ($) $ in Millions | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Dec. 31, 2013
--- | --- | --- | --- | --- | --- | ---
Assets: |  |  |  |  |  |
Marketable debt securities | $ 3,188.4 |  | $ 2,111.1 |  |  |
Fair Value, Measurements, Recurring |  |  |  |  |  |
Assets: |  |  |  |  |  |
Cash equivalents | 974.0 |  | 716.3 |  |  |
Investments | 6.8 |  | 6.9 |  |  |
Derivative contracts | 100.5 |  | 72.7 |  |  |
Plan assets for deferred compensation | 40.7 |  | 36.9 |  |  |
Total | 4,310.4 |  | 2,943.9 |  |  |
Liabilities: |  |  |  |  |  |
Derivative contracts | 27.7 |  | 5.4 |  |  |
Contingent consideration obligations | 495.6 | $ 461.8 | 215.5 | $ 279.1 | $ 275.1 | $ 280.9
Total | 523.3 |  | 220.9 |  |  |
Fair Value, Measurements, Recurring | Corporate debt securities |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable debt securities | 1,198.1 |  | 1,063.0 |  |  |
Fair Value, Measurements, Recurring | Government securities |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable debt securities | 1,700.3 |  | 849.8 |  |  |
Fair Value, Measurements, Recurring | Mortgage and other asset backed securities |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable debt securities | 290.0 |  | 198.3 |  |  |
Quoted Prices in Active Markets, Level 1 | Fair Value, Measurements, Recurring |  |  |  |  |  |
Assets: |  |  |  |  |  |
Cash equivalents | 0.0 |  | 0.0 |  |  |
Investments | 6.8 |  | 6.9 |  |  |
Derivative contracts | 0.0 |  | 0.0 |  |  |
Plan assets for deferred compensation | 0.0 |  | 0.0 |  |  |
Total | 6.8 |  | 6.9 |  |  |
Liabilities: |  |  |  |  |  |
Derivative contracts | 0.0 |  | 0.0 |  |  |
Contingent consideration obligations | 0.0 |  | 0.0 |  |  |
Total | 0.0 |  | 0.0 |  |  |
Quoted Prices in Active Markets, Level 1 | Fair Value, Measurements, Recurring | Corporate debt securities |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable debt securities | 0.0 |  | 0.0 |  |  |
Quoted Prices in Active Markets, Level 1 | Fair Value, Measurements, Recurring | Government securities |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable debt securities | 0.0 |  | 0.0 |  |  |
Quoted Prices in Active Markets, Level 1 | Fair Value, Measurements, Recurring | Mortgage and other asset backed securities |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable debt securities | 0.0 |  | 0.0 |  |  |
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring |  |  |  |  |  |
Assets: |  |  |  |  |  |
Cash equivalents | 974.0 |  | 716.3 |  |  |
Investments | 0.0 |  | 0.0 |  |  |
Derivative contracts | 100.5 |  | 72.7 |  |  |
Plan assets for deferred compensation | 40.7 |  | 36.9 |  |  |
Total | 4,303.6 |  | 2,937.0 |  |  |
Liabilities: |  |  |  |  |  |
Derivative contracts | 27.7 |  | 5.4 |  |  |
Contingent consideration obligations | 0.0 |  | 0.0 |  |  |
Total | 27.7 |  | 5.4 |  |  |
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Corporate debt securities |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable debt securities | 1,198.1 |  | 1,063.0 |  |  |
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Government securities |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable debt securities | 1,700.3 |  | 849.8 |  |  |
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Mortgage and other asset backed securities |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable debt securities | 290.0 |  | 198.3 |  |  |
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring |  |  |  |  |  |
Assets: |  |  |  |  |  |
Cash equivalents | 0.0 |  | 0.0 |  |  |
Investments | 0.0 |  | 0.0 |  |  |
Derivative contracts | 0.0 |  | 0.0 |  |  |
Plan assets for deferred compensation | 0.0 |  | 0.0 |  |  |
Total | 0.0 |  | 0.0 |  |  |
Liabilities: |  |  |  |  |  |
Derivative contracts | 0.0 |  | 0.0 |  |  |
Contingent consideration obligations | 495.6 |  | 215.5 |  |  |
Total | 495.6 |  | 215.5 |  |  |
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | Corporate debt securities |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable debt securities | 0.0 |  | 0.0 |  |  |
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | Government securities |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable debt securities | 0.0 |  | 0.0 |  |  |
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | Mortgage and other asset backed securities |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable debt securities | $ 0.0 |  | $ 0.0 |  |  |

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