CECL (Details 4) - CHF (SFr)
SFr in Millions
 3 Months Ended 12 Months Ended
Dec. 31, 2021
Sep. 30, 2021
Jun. 30, 2021
Mar. 31, 2021
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Other financial assets, Held At Amortized Cost, Allowance for Credit Losses [Roll Forward]              
Cash and due from banks, held at amortized cost, Allowance for Credit Loss, Beginning Balance       SFr 6 SFr 6    
Interest-bearing deposits with banks, held at amortized cost, Allowance for Credit Loss, Beginning Balance       5 5    
Securities purchased under resale agreements and securities borrowing transactions, held at amortized cost, Allowance for Credit Loss, Beginning Balance       (0) (0)    
Brokerage receivables, held at amortized cost, Allowance for Credit Loss, Beginning Balance       1 1    
Other assets, held at amortized cost, Allowance for Credit Loss, Beginning Balance       43 43    
Other financial assets, held at amortized cost, Allowance for Credit Loss, Beginning Balance       55 55 SFr 45  
Other financial assets, Current-period provision for expected credit losses         4,291 24 SFr 11
Other financial assets, Gross write-offs         (9) (12)  
Other financial assets, Recovery         0 2  
Other financial assets, Net write-offs         (9) (10)  
Other financial assets, Foreign currency translation impact and other adjustments, net         (121) (4)  
Cash and due from banks, held at amortized cost, Allowance for Credit Loss, Ending Balance SFr (0)       (0) 6  
Interest-bearing deposits with banks, held at amortized cost, Allowance for Credit Loss, Ending Balance (0)       (0) 5  
Securities purchased under resale agreements and securities borrowing transactions, held at amortized cost, Allowance for Credit Loss, Ending Balance (0)       (0) (0)  
Brokerage receivables, held at amortized cost, Allowance for Credit Loss, Ending Balance 4,186       4,186 1  
Other assets, held at amortized cost, Allowance for Credit Loss, Ending Balance 30       30 43  
Other financial assets, held at amortized cost, Allowance for Credit Loss, Ending Balance 4,216       4,216 55 45
Other financial assets, individually evaluated 4,202       4,202 17  
Other financial assets, collectively evaluated 14       14 38  
Archegos Capital Management [Member]              
Other financial assets, Held At Amortized Cost, Allowance for Credit Losses [Roll Forward]              
Other financial assets, Current-period provision for expected credit losses (5) SFr (188) SFr 70 4,430 4,307    
Bank              
Other financial assets, Held At Amortized Cost, Allowance for Credit Losses [Roll Forward]              
Cash and due from banks, held at amortized cost, Allowance for Credit Loss, Beginning Balance       1 1    
Interest-bearing deposits with banks, held at amortized cost, Allowance for Credit Loss, Beginning Balance       5 5    
Securities purchased under resale agreements and securities borrowing transactions, held at amortized cost, Allowance for Credit Loss, Beginning Balance       (0) (0)    
Brokerage receivables, held at amortized cost, Allowance for Credit Loss, Beginning Balance       1 1    
Other assets, held at amortized cost, Allowance for Credit Loss, Beginning Balance       41 41    
Other financial assets, held at amortized cost, Allowance for Credit Loss, Beginning Balance       SFr 48 48 43  
Other financial assets, Current-period provision for expected credit losses         4,295 19 11
Other financial assets, Gross write-offs         (8) (12)  
Other financial assets, Recovery         0 2  
Other financial assets, Net write-offs         (8) (10)  
Other financial assets, Foreign currency translation impact and other adjustments, net         (121) (4)  
Cash and due from banks, held at amortized cost, Allowance for Credit Loss, Ending Balance (0)       (0) 1  
Interest-bearing deposits with banks, held at amortized cost, Allowance for Credit Loss, Ending Balance (0)       (0) 5  
Securities purchased under resale agreements and securities borrowing transactions, held at amortized cost, Allowance for Credit Loss, Ending Balance (0)       (0) (0)  
Brokerage receivables, held at amortized cost, Allowance for Credit Loss, Ending Balance 4,186       4,186 1  
Other assets, held at amortized cost, Allowance for Credit Loss, Ending Balance 28       28 41  
Other financial assets, held at amortized cost, Allowance for Credit Loss, Ending Balance 4,214       4,214 48 SFr 43
Other financial assets, individually evaluated 4,200       4,200 15  
Other financial assets, collectively evaluated SFr 14       14 SFr 33  
Bank | Archegos Capital Management [Member]              
Other financial assets, Held At Amortized Cost, Allowance for Credit Losses [Roll Forward]              
Other financial assets, Current-period provision for expected credit losses         SFr 4,307