Segment and Geographical Area Information (Details) (Table 3) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Segment Reporting [Line Items]
Depreciation	$ 33.9	$ 31.9	$ 99.2	$ 97.9
Stock-based compensation expense			54.7	46.1
Operating Segments
Segment Reporting [Line Items]
Depreciation	22.9	27.6	68.4	83.7
Operating Segments \| Morningstar Data and Analytics Segment
Segment Reporting [Line Items]
Depreciation	9.5	11.3	28.2	33.3
Operating Segments \| PitchBook Segment
Segment Reporting [Line Items]
Depreciation	8.5	8.7	25.2	24.6
Operating Segments \| Morningstar Credit Segment
Segment Reporting [Line Items]
Depreciation	1.1	3.0	3.9	11.9
Operating Segments \| Morningstar Wealth Segment
Segment Reporting [Line Items]
Depreciation	1.5	2.0	4.3	6.0
Operating Segments \| Morningstar Retirement Segment
Segment Reporting [Line Items]
Depreciation	2.3	2.6	6.8	7.9
Operating Segments \| Corporate and Other
Segment Reporting [Line Items]
Depreciation	$ 11.0	$ 4.3	$ 30.8	$ 14.2

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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