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Revenue and Related Matters - Narrative (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2020 USD ($) segment | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($)
Disaggregation of Revenue [Line Items] |  |  |
Number of reportable segments | segment | 3 |  |
Revenue recognized previously attributable to deferred revenues | $ 1,494.0 | $ 1,436.9 | $ 1,287.8
Revenue reserve balance | 10.0 | 7.8 |
Amortization of deferred sales commissions | $ 440.5 | $ 369.5 | $ 304.8
Research | Product Concentration Risk | Revenue from Contract with Customer Benchmark |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Concentration risk percentage | 92.00% |  |
Minimum |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Percentage of subscription contracts billable upon signing for twelve months of service | 80.00% |  |
Maximum |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Percentage of subscription contracts billable upon signing for twelve months of service | 85.00% |  |

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- Definition The amount of expense recognized in the current period for the periodic realization of capitalized fees that were paid to salespeople, distributors, brokers, and agents at the time of the conclusion of the sale. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.3) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 + Details
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