Segment Reporting (Details) - Table 3 - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation expense	$ 125.4	$ 113.2	$ 97.8
Stock-based compensation expense	54.7	52.8	83.2
Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation expense	107.1	93.7	82.1
Stock-based compensation expense	22.2	35.9	64.3
Morningstar Data and Analytics Segment [Member] | Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation expense	37.9	31.0	23.4
Stock-based compensation expense	5.7	10.6	10.5
PitchBook Segment [Member] | Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation expense	31.8	26.8	23.8
Stock-based compensation expense	4.4	10.3	40.2
Morningstar Wealth Segment [Member] | Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation expense	18.5	15.8	18.1
Stock-based compensation expense	3.9	6.4	5.7
Morningstar Credit Segment [Member] | Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation expense	8.9	9.1	8.9
Stock-based compensation expense	6.7	7.0	6.3
Morningstar Retirement Segment [Member] | Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation expense	10.0	11.0	7.9
Stock-based compensation expense	1.5	1.6	1.6
Corporate Segment and Other Operating Segment | Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation expense	18.3	19.5	15.7
Stock-based compensation expense	$ 32.5	$ 16.9	$ 18.9