Segment and Geographical Area Information (Details) (Table 1) $ in Millions	3 Months Ended
Mar. 31, 2025 USD ($) segments	Mar. 31, 2024 USD ($)
Segment Reporting Information [Line Items]
Consolidated revenue	$ 581.9	$ 542.8
Number of Operating Segments \| segments	7
Number of Reportable Segments \| segments	5
Operating Segments
Segment Reporting Information [Line Items]
Consolidated revenue	$ 530.1	492.0
Reportable Segment Profitability	174.6	152.1
Morningstar Data and Analytics Segment
Segment Reporting Information [Line Items]
Consolidated revenue	199.2	196.7
Compensation Expense, Excluding Cost of Good and Service Sold	57.7	53.6
Segment Reporting, Other Segment Item, Amount	54.4	51.9
Morningstar Data and Analytics Segment \| Operating Segments
Segment Reporting Information [Line Items]
Reportable Segment Profitability	87.1	91.2
PitchBook Segment
Segment Reporting Information [Line Items]
Consolidated revenue	163.7	147.6
Compensation Expense, Excluding Cost of Good and Service Sold	76.1	76.1
Segment Reporting, Other Segment Item, Amount	35.3	31.5
PitchBook Segment \| Operating Segments
Segment Reporting Information [Line Items]
Reportable Segment Profitability	52.3	40.0
Morningstar Credit Segment
Segment Reporting Information [Line Items]
Consolidated revenue	61.3	59.0
Compensation Expense, Excluding Cost of Good and Service Sold	30.2	32.4
Segment Reporting, Other Segment Item, Amount	31.9	32.2
Morningstar Credit Segment \| Operating Segments
Segment Reporting Information [Line Items]
Reportable Segment Profitability	(0.8)	(5.6)
Morningstar Wealth Segment
Segment Reporting Information [Line Items]
Consolidated revenue	73.0	60.3
Compensation Expense, Excluding Cost of Good and Service Sold	38.5	35.4
Segment Reporting, Other Segment Item, Amount	13.1	12.6
Morningstar Wealth Segment \| Operating Segments
Segment Reporting Information [Line Items]
Reportable Segment Profitability	21.4	12.3
Morningstar Retirement Segment
Segment Reporting Information [Line Items]
Consolidated revenue	32.9	28.4
Compensation Expense, Excluding Cost of Good and Service Sold	11.6	10.5
Segment Reporting, Other Segment Item, Amount	6.7	3.7
Morningstar Retirement Segment \| Operating Segments
Segment Reporting Information [Line Items]
Reportable Segment Profitability	14.6	14.2
License-based
Segment Reporting Information [Line Items]
Consolidated revenue	418.0	400.2
License-based \| Operating Segments
Segment Reporting Information [Line Items]
Consolidated revenue	385.2	367.5
License-based \| Morningstar Data and Analytics Segment
Segment Reporting Information [Line Items]
Consolidated revenue	199.2	196.7
License-based \| PitchBook Segment
Segment Reporting Information [Line Items]
Consolidated revenue	161.8	145.6
License-based \| Morningstar Credit Segment
Segment Reporting Information [Line Items]
Consolidated revenue	19.1	20.5
License-based \| Morningstar Wealth Segment
Segment Reporting Information [Line Items]
Consolidated revenue	4.6	4.2
License-based \| Morningstar Retirement Segment
Segment Reporting Information [Line Items]
Consolidated revenue	0.5	0.5
Asset-based
Segment Reporting Information [Line Items]
Consolidated revenue	85.7	77.0
Asset-based \| Operating Segments
Segment Reporting Information [Line Items]
Consolidated revenue	68.5	61.5
Asset-based \| Morningstar Data and Analytics Segment
Segment Reporting Information [Line Items]
Consolidated revenue	0.0	0.0
Asset-based \| PitchBook Segment
Segment Reporting Information [Line Items]
Consolidated revenue	0.0	0.0
Asset-based \| Morningstar Credit Segment
Segment Reporting Information [Line Items]
Consolidated revenue	36.1	33.6
Asset-based \| Morningstar Wealth Segment
Segment Reporting Information [Line Items]
Consolidated revenue	0.0	0.0
Asset-based \| Morningstar Retirement Segment
Segment Reporting Information [Line Items]
Consolidated revenue	32.4	27.9
Transaction-based
Segment Reporting Information [Line Items]
Consolidated revenue	78.2	65.6
Transaction-based \| Operating Segments
Segment Reporting Information [Line Items]
Consolidated revenue	76.4	63.0
Transaction-based \| Morningstar Data and Analytics Segment
Segment Reporting Information [Line Items]
Consolidated revenue	0.0	0.0
Transaction-based \| PitchBook Segment
Segment Reporting Information [Line Items]
Consolidated revenue	1.9	2.0
Transaction-based \| Morningstar Credit Segment
Segment Reporting Information [Line Items]
Consolidated revenue	6.1	4.9
Transaction-based \| Morningstar Wealth Segment
Segment Reporting Information [Line Items]
Consolidated revenue	68.4	56.1
Transaction-based \| Morningstar Retirement Segment
Segment Reporting Information [Line Items]
Consolidated revenue	$ 0.0	$ 0.0

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