Segment and Geographical Area Information (Details) (Table 1) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) segments	Jun. 30, 2024 USD ($)
Segment Reporting Information [Line Items]
Consolidated revenue	$ 605.1	$ 571.9	$ 1,187.0	$ 1,114.7
Number of Operating Segments \| segments			7
Number of Reportable Segments \| segments			5
Operating Segments
Segment Reporting Information [Line Items]
Consolidated revenue	557.4	522.1	$ 1,087.5	1,014.1
Reportable Segment Profitability	198.0	177.6	372.6	329.7
Morningstar Data and Analytics Segment
Segment Reporting Information [Line Items]
Consolidated revenue	209.2	196.9	408.4	393.6
Compensation Expense, Excluding Cost of Good and Service Sold	58.2	54.0	115.9	107.6
Segment Reporting, Other Segment Item, Amount	54.7	55.6	109.1	107.5
Morningstar Data and Analytics Segment \| Operating Segments
Segment Reporting Information [Line Items]
Reportable Segment Profitability	96.3	87.3	183.4	178.5
PitchBook Segment
Segment Reporting Information [Line Items]
Consolidated revenue	166.5	151.7	330.2	299.3
Compensation Expense, Excluding Cost of Good and Service Sold	76.3	70.2	152.4	146.3
Segment Reporting, Other Segment Item, Amount	37.4	34.2	72.7	65.7
PitchBook Segment \| Operating Segments
Segment Reporting Information [Line Items]
Reportable Segment Profitability	52.8	47.3	105.1	87.3
Morningstar Credit Segment
Segment Reporting Information [Line Items]
Consolidated revenue	64.3	62.6	158.0	121.6
Compensation Expense, Excluding Cost of Good and Service Sold	28.7	31.2	58.9	63.6
Segment Reporting, Other Segment Item, Amount	32.6	33.6	64.5	65.8
Morningstar Credit Segment \| Operating Segments
Segment Reporting Information [Line Items]
Reportable Segment Profitability	3.0	(2.2)	2.2	(7.8)
Morningstar Wealth Segment
Segment Reporting Information [Line Items]
Consolidated revenue	85.0	77.6	125.6	137.9
Compensation Expense, Excluding Cost of Good and Service Sold	41.1	37.7	79.6	73.1
Segment Reporting, Other Segment Item, Amount	13.4	12.0	26.5	24.6
Morningstar Wealth Segment \| Operating Segments
Segment Reporting Information [Line Items]
Reportable Segment Profitability	30.5	27.9	51.9	40.2
Morningstar Retirement Segment
Segment Reporting Information [Line Items]
Consolidated revenue	32.4	33.3	65.3	61.7
Compensation Expense, Excluding Cost of Good and Service Sold	11.3	10.8	22.9	21.3
Segment Reporting, Other Segment Item, Amount	5.7	5.2	12.4	8.9
Morningstar Retirement Segment \| Operating Segments
Segment Reporting Information [Line Items]
Reportable Segment Profitability	15.4	17.3	30.0	31.5
License-based
Segment Reporting Information [Line Items]
Consolidated revenue	428.4	401.7	846.4	801.9
License-based \| Operating Segments
Segment Reporting Information [Line Items]
Consolidated revenue	397.5	369.9	782.7	737.4
License-based \| Morningstar Data and Analytics Segment
Segment Reporting Information [Line Items]
Consolidated revenue	207.7	195.7	406.9	392.4
License-based \| PitchBook Segment
Segment Reporting Information [Line Items]
Consolidated revenue	164.7	150.1	326.5	295.7
License-based \| Morningstar Credit Segment
Segment Reporting Information [Line Items]
Consolidated revenue	19.7	19.9	9.6	40.4
License-based \| Morningstar Wealth Segment
Segment Reporting Information [Line Items]
Consolidated revenue	5.0	3.7	38.8	7.9
License-based \| Morningstar Retirement Segment
Segment Reporting Information [Line Items]
Consolidated revenue	0.4	0.5	0.9	1.0
Asset-based
Segment Reporting Information [Line Items]
Consolidated revenue	82.4	84.7	168.1	161.7
Asset-based \| Operating Segments
Segment Reporting Information [Line Items]
Consolidated revenue	67.2	68.6	135.7	130.1
Asset-based \| Morningstar Data and Analytics Segment
Segment Reporting Information [Line Items]
Consolidated revenue	0.0	0.0	0.0	0.0
Asset-based \| PitchBook Segment
Segment Reporting Information [Line Items]
Consolidated revenue	0.0	0.0	0.0	0.0
Asset-based \| Morningstar Credit Segment
Segment Reporting Information [Line Items]
Consolidated revenue	35.2	35.8	0.0	69.4
Asset-based \| Morningstar Wealth Segment
Segment Reporting Information [Line Items]
Consolidated revenue	0.0	0.0	71.3	0.0
Asset-based \| Morningstar Retirement Segment
Segment Reporting Information [Line Items]
Consolidated revenue	32.0	32.8	64.4	60.7
Transaction-based
Segment Reporting Information [Line Items]
Consolidated revenue	94.3	85.5	172.5	151.1
Transaction-based \| Operating Segments
Segment Reporting Information [Line Items]
Consolidated revenue	92.7	83.6	169.1	146.6
Transaction-based \| Morningstar Data and Analytics Segment
Segment Reporting Information [Line Items]
Consolidated revenue	1.5	1.2	1.5	1.2
Transaction-based \| PitchBook Segment
Segment Reporting Information [Line Items]
Consolidated revenue	1.8	1.6	3.7	3.6
Transaction-based \| Morningstar Credit Segment
Segment Reporting Information [Line Items]
Consolidated revenue	9.4	6.9	148.4	11.8
Transaction-based \| Morningstar Wealth Segment
Segment Reporting Information [Line Items]
Consolidated revenue	80.0	73.9	15.5	130.0
Transaction-based \| Morningstar Retirement Segment
Segment Reporting Information [Line Items]
Consolidated revenue	$ 0.0	$ 0.0	$ 0.0	$ 0.0

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