Segment Reporting (Details) - Table 2 $ in Millions, ¥ in Billions					12 Months Ended
	Apr. 19, 2023 USD ($)	Apr. 19, 2023 JPY (¥)	Apr. 06, 2023 USD ($)	Apr. 06, 2023 JPY (¥)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Revenue					$ 2,275.1	$ 2,038.6	$ 1,870.6
Amortization expense					(64.5)	(70.5)	(66.7)
Business Combination, Acquisition and Integration Related Costs					(8.5)	(9.8)	(17.1)
Gain on sale of customer assets					64.0	0.0	0.0
Business Combination, Contingent Consideration Expense					0.0	0.0	(11.6)
Severance and personnel expenses					0.0	(5.5)	(27.5)
Business Exit Costs	$ (14.8)	¥ (2.0)	$ (45.1)	¥ (6.0)	0.0	(7.0)	(8.2)
Asset Impairment Charges					0.0	(3.1)	0.0
Operating income					484.8	230.6	167.8
Non-operating income (expense), net					6.5	(49.1)	(37.2)
Equity in investments of unconsolidated entities					(17.4)	(7.4)	(3.6)
Income Loss From Continuing Operations Before Income Taxes Domestic And Foreign					473.9	174.1	127.0
Unallocated Corporate Expenses					181.4	153.5	135.8
Finance Lease, Right-of-Use Asset, Amortization					0.5	1.2	2.1
Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [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, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Revenue					788.1	747.2	696.6
Morningstar Data and Analytics Segment [Member] | Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Reportable Segment Profitability					355.4	339.8	313.3
PitchBook Segment [Member]
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Revenue					618.4	551.9	450.7
PitchBook Segment [Member] | Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Reportable Segment Profitability					186.4	148.1	71.5
Morningstar Wealth Segment [Member]
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Revenue					248.4	229.9	228.9
Morningstar Wealth Segment [Member] | Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Reportable Segment Profitability					(9.3)	(40.4)	(14.3)
Morningstar Credit Segment [Member]
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Revenue					291.1	215.4	236.9
Morningstar Credit Segment [Member] | Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Reportable Segment Profitability					75.6	21.7	59.1
Morningstar Retirement Segment [Member]
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Revenue					127.1	110.5	104.0
Morningstar Retirement Segment [Member] | Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Reportable Segment Profitability					65.6	54.1	51.4
Corporate Segment and Other Operating Segment | Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Revenue					202.0	183.7	153.5
Reportable Segment Profitability					(179.9)	(196.8)	(182.1)
Morningstar Sustainalytics [Member]
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Revenue					117.3	118.2	103.3
Morningstar Indexes [Member]
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Revenue					$ 84.7	$ 65.5	$ 50.2