Segment and Geographical Area Information (Details) (Table 3) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation	$ 32.6	$ 32.8
Stock-based compensation expense	10.8	9.1
Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation	22.7	27.7
Operating Segments \| Morningstar Data and Analytics Segment
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation	9.5	10.8
Operating Segments \| PitchBook Segment
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation	7.9	7.8
Operating Segments \| Morningstar Credit Segment
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation	1.6	4.5
Operating Segments \| Morningstar Wealth Segment
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation	1.4	2.0
Operating Segments \| Morningstar Retirement Segment
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation	2.3	2.6
Operating Segments \| Corporate and Other
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Depreciation	$ 9.9	$ 5.1