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Fair Value Measurements (Details 1) - USD ($) $ in Millions | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Debt Instrument |  |
Notes payable, fair value | $ 6,553.6 | $ 6,037.6
2.90% Senior Notes due 2020 |  |
Debt Instrument |  |
Notes payable, fair value | 1,509.6 | 1,489.5
3.625% Senior Notes due 2022 |  |
Debt Instrument |  |
Notes payable, fair value | 1,038.9 | 1,000.4
4.05% Senior Notes due 2025 |  |
Debt Instrument |  |
Notes payable, fair value | 1,897.2 | 1,745.1
5.20% Senior Notes due 2045 |  |
Debt Instrument |  |
Notes payable, fair value | $ 2,107.9 | $ 1,802.6

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- Definition Fair value portion of notes payable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19,20,22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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