Fair Value Measurements (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Assets:
Marketable debt securities	$ 3,004.0	$ 2,433.1
Fair Value, Measurements, Recurring
Assets:
Cash equivalents	1,283.7	1,632.2
Marketable equity securities	860.3	1,048.5
Derivative contracts	97.2	80.9
Plan assets for deferred compensation	35.8	33.4
Total	5,281.0	5,228.1
Liabilities:
Derivative contracts	12.5	10.8
Contingent consideration obligations	202.0	209.1	$ 226.0	$ 259.8
Total	214.5	219.9
Fair Value, Measurements, Recurring | Corporate debt securities
Assets:
Marketable debt securities	1,579.4	1,108.2
Fair Value, Measurements, Recurring | Government securities
Assets:
Marketable debt securities	1,252.7	1,192.7
Fair Value, Measurements, Recurring | Mortgage and other asset backed securities
Assets:
Marketable debt securities	171.9	132.2
Quoted Prices in Active Markets (Level 1) | Fair Value, Measurements, Recurring
Assets:
Cash equivalents	0.0	0.0
Marketable equity securities	607.0	181.7
Derivative contracts	0.0	0.0
Plan assets for deferred compensation	0.0	0.0
Total	607.0	181.7
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	1,283.7	1,632.2
Marketable equity securities	253.3	866.8
Derivative contracts	97.2	80.9
Plan assets for deferred compensation	35.8	33.4
Total	4,674.0	5,046.4
Liabilities:
Derivative contracts	12.5	10.8
Contingent consideration obligations	0.0	0.0
Total	12.5	10.8
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Corporate debt securities
Assets:
Marketable debt securities	1,579.4	1,108.2
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Government securities
Assets:
Marketable debt securities	1,252.7	1,192.7
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Mortgage and other asset backed securities
Assets:
Marketable debt securities	171.9	132.2
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Assets:
Cash equivalents	0.0	0.0
Marketable equity securities	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	202.0	209.1
Total	202.0	209.1
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