Segment and Geographical Area Information (Details) (Table 3) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation	$ 32.8	$ 29.2
Stock-based compensation expense	9.1	11.4
Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation	27.7	25.0
Operating Segments | Morningstar Data and Analytics Segment
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation	10.8	8.2
Operating Segments | PitchBook Segment
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation	7.8	7.4
Operating Segments | Morningstar Credit Segment
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation	4.5	4.7
Operating Segments | Morningstar Wealth Segment
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation	2.0	1.9
Operating Segments | Morningstar Retirement Segment
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation	2.6	2.8
Operating Segments | Corporate and Other
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation	$ 5.1	$ 4.2