Segment Reporting (Details) - Table 1 $ in Millions	12 Months Ended
Dec. 31, 2024 USD ($) segments	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Segment Reporting Information [Line Items]
Revenue	$ 2,275.1	$ 2,038.6	$ 1,870.6
Number of Operating Segments \| segments	7
Number of Reportable Segments \| segments	5
Operating Segments
Segment Reporting Information [Line Items]
Revenue	$ 2,073.1	1,854.9	1,717.1
Reportable Segment Profitability	673.7	523.3	481.0
Morningstar Data and Analytics Segment [Member]
Segment Reporting Information [Line Items]
Revenue	788.1	747.2	696.6
Compensation Expense, Excluding Cost of Good and Service Sold	216.1	173.8	161.9
Segment Reporting, Other Segment Item, Amount	216.6	233.6	221.4
Morningstar Data and Analytics Segment [Member] \| Operating Segments
Segment Reporting Information [Line Items]
Reportable Segment Profitability	355.4	339.8	313.3
PitchBook Segment [Member]
Segment Reporting Information [Line Items]
Revenue	618.4	551.9	450.7
Compensation Expense, Excluding Cost of Good and Service Sold	289.5	281.0	263.3
Segment Reporting, Other Segment Item, Amount	142.5	122.8	115.9
PitchBook Segment [Member] \| Operating Segments
Segment Reporting Information [Line Items]
Reportable Segment Profitability	186.4	148.1	71.5
Morningstar Wealth Segment [Member]
Segment Reporting Information [Line Items]
Revenue	248.4	229.9	228.9
Compensation Expense, Excluding Cost of Good and Service Sold	124.6	151.5	129.2
Segment Reporting, Other Segment Item, Amount	133.1	118.8	114.0
Morningstar Wealth Segment [Member] \| Operating Segments
Segment Reporting Information [Line Items]
Reportable Segment Profitability	(9.3)	(40.4)	(14.3)
Morningstar Credit Segment [Member]
Segment Reporting Information [Line Items]
Revenue	291.1	215.4	236.9
Compensation Expense, Excluding Cost of Good and Service Sold	162.5	128.2	124.2
Segment Reporting, Other Segment Item, Amount	53.0	65.5	53.6
Morningstar Credit Segment [Member] \| Operating Segments
Segment Reporting Information [Line Items]
Reportable Segment Profitability	75.6	21.7	59.1
Morningstar Retirement Segment [Member]
Segment Reporting Information [Line Items]
Revenue	127.1	110.5	104.0
Compensation Expense, Excluding Cost of Good and Service Sold	43.9	41.0	37.0
Segment Reporting, Other Segment Item, Amount	17.6	15.4	15.6
Morningstar Retirement Segment [Member] \| Operating Segments
Segment Reporting Information [Line Items]
Reportable Segment Profitability	65.6	54.1	51.4
Corporate Segment and Other Operating Segment \| Operating Segments
Segment Reporting Information [Line Items]
Revenue	202.0	183.7	153.5
Reportable Segment Profitability	(179.9)	(196.8)	(182.1)
License-based \| Operating Segments
Segment Reporting Information [Line Items]
Revenue	1,496.9	1,391.6	1,228.7
License-based \| Morningstar Data and Analytics Segment [Member]
Segment Reporting Information [Line Items]
Revenue	786.7	745.5	695.1
License-based \| PitchBook Segment [Member]
Segment Reporting Information [Line Items]
Revenue	611.6	551.9	450.7
License-based \| Morningstar Wealth Segment [Member]
Segment Reporting Information [Line Items]
Revenue	80.4	80.8	80.9
License-based \| Morningstar Credit Segment [Member]
Segment Reporting Information [Line Items]
Revenue	16.4	11.7	0.0
License-based \| Morningstar Retirement Segment [Member]
Segment Reporting Information [Line Items]
Revenue	1.8	1.7	2.0
Asset-based \| Operating Segments
Segment Reporting Information [Line Items]
Revenue	267.6	231.1	219.4
Asset-based \| Morningstar Data and Analytics Segment [Member]
Segment Reporting Information [Line Items]
Revenue	0.0	0.0	0.0
Asset-based \| PitchBook Segment [Member]
Segment Reporting Information [Line Items]
Revenue	0.0	0.0	0.0
Asset-based \| Morningstar Wealth Segment [Member]
Segment Reporting Information [Line Items]
Revenue	142.3	122.6	117.6
Asset-based \| Morningstar Credit Segment [Member]
Segment Reporting Information [Line Items]
Revenue	0.0	0.0	0.0
Asset-based \| Morningstar Retirement Segment [Member]
Segment Reporting Information [Line Items]
Revenue	125.3	108.5	101.8
Transaction-based \| Operating Segments
Segment Reporting Information [Line Items]
Revenue	308.6	232.2	269.0
Transaction-based \| Morningstar Data and Analytics Segment [Member]
Segment Reporting Information [Line Items]
Revenue	1.4	1.7	1.5
Transaction-based \| PitchBook Segment [Member]
Segment Reporting Information [Line Items]
Revenue	6.8	0.0	0.0
Transaction-based \| Morningstar Wealth Segment [Member]
Segment Reporting Information [Line Items]
Revenue	25.7	26.5	30.4
Transaction-based \| Morningstar Credit Segment [Member]
Segment Reporting Information [Line Items]
Revenue	274.7	203.7	236.9
Transaction-based \| Morningstar Retirement Segment [Member]
Segment Reporting Information [Line Items]
Revenue	$ 0.0	$ 0.3	$ 0.2

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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