v3.25.2
Acquisitions, Goodwill and Other Intangible Assets (Schedule of Goodwill) (Details) - USD ($)
$ in Millions
 6 Months Ended
Jun. 01, 2022
Jun. 30, 2025
Business Combination [Line Items]    
Goodwill   $ 1,618.2
Goodwill [Roll Forward]    
Goodwill, Beginning Balance   1,562.0
Foreign currency translation   24.1
Goodwill, Ending Balance   1,618.2
Operating Segments    
Business Combination [Line Items]    
Goodwill   1,548.1
Goodwill [Roll Forward]    
Goodwill, Beginning Balance   1,492.8
Foreign currency translation   23.2
Goodwill, Ending Balance   1,548.1
Morningstar Data and Analytics Segment | Operating Segments    
Business Combination [Line Items]    
Goodwill   610.2
Goodwill [Roll Forward]    
Goodwill, Beginning Balance   594.0
Foreign currency translation   16.2
Goodwill, Ending Balance   610.2
PitchBook Segment | Operating Segments    
Business Combination [Line Items]    
Goodwill   629.8
Goodwill [Roll Forward]    
Goodwill, Beginning Balance   607.4
Foreign currency translation   0.0
Goodwill, Ending Balance   629.8
Morningstar Credit Segment | Operating Segments    
Business Combination [Line Items]    
Goodwill   120.2
Goodwill [Roll Forward]    
Goodwill, Beginning Balance   105.2
Foreign currency translation   5.3
Goodwill, Ending Balance   120.2
Morningstar Wealth Segment | Operating Segments    
Business Combination [Line Items]    
Goodwill   94.4
Goodwill [Roll Forward]    
Goodwill, Beginning Balance   92.7
Foreign currency translation   1.7
Goodwill, Ending Balance   94.4
Morningstar Retirement Segment | Operating Segments    
Business Combination [Line Items]    
Goodwill   93.5
Goodwill [Roll Forward]    
Goodwill, Beginning Balance   93.5
Foreign currency translation   0.0
Goodwill, Ending Balance   93.5
Corporate and Other | Operating Segments    
Business Combination [Line Items]    
Goodwill   70.1
Goodwill [Roll Forward]    
Goodwill, Beginning Balance   69.2
Foreign currency translation   0.9
Goodwill, Ending Balance   70.1
DealX    
Business Combination [Line Items]    
Goodwill, Acquired During Period   9.7
DealX | Operating Segments    
Business Combination [Line Items]    
Goodwill, Acquired During Period   9.7
DealX | Morningstar Data and Analytics Segment | Operating Segments    
Business Combination [Line Items]    
Goodwill, Acquired During Period   0.0
DealX | PitchBook Segment | Operating Segments    
Business Combination [Line Items]    
Goodwill, Acquired During Period   0.0
DealX | Morningstar Credit Segment | Operating Segments    
Business Combination [Line Items]    
Goodwill, Acquired During Period   9.7
DealX | Morningstar Wealth Segment | Operating Segments    
Business Combination [Line Items]    
Goodwill, Acquired During Period   0.0
DealX | Morningstar Retirement Segment | Operating Segments    
Business Combination [Line Items]    
Goodwill, Acquired During Period   0.0
DealX | Corporate and Other | Operating Segments    
Business Combination [Line Items]    
Goodwill, Acquired During Period   0.0
Lumonic    
Business Combination [Line Items]    
Goodwill, Acquired During Period $ 22.4  
Lumonic | Operating Segments    
Business Combination [Line Items]    
Goodwill, Acquired During Period   22.4
Lumonic | Morningstar Data and Analytics Segment | Operating Segments    
Business Combination [Line Items]    
Goodwill, Acquired During Period   0.0
Lumonic | PitchBook Segment | Operating Segments    
Business Combination [Line Items]    
Goodwill, Acquired During Period   22.4
Lumonic | Morningstar Credit Segment | Operating Segments    
Business Combination [Line Items]    
Goodwill, Acquired During Period   0.0
Lumonic | Morningstar Wealth Segment | Operating Segments    
Business Combination [Line Items]    
Goodwill, Acquired During Period   0.0
Lumonic | Morningstar Retirement Segment | Operating Segments    
Business Combination [Line Items]    
Goodwill, Acquired During Period   0.0
Lumonic | Corporate and Other | Operating Segments    
Business Combination [Line Items]    
Goodwill, Acquired During Period   $ 0.0