Investment securities - Unrealized losses/fair value (Details 3) - CHF (SFr) SFr in Millions	Jun. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract]
Fair value, less than 12 months	SFr 179	SFr 374
Fair value, 12 months or more	666	404
Fair value, total	845	778
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Gross unrealized losses, less than 12 months	6	58
Gross unrealized losses, 12 months or more	144	98
Gross unrealized losses, total	150	156
Corporate debt securities
Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract]
Fair value, less than 12 months	179	374
Fair value, 12 months or more	666	404
Fair value, total	845	778
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Gross unrealized losses, less than 12 months	6	58
Gross unrealized losses, 12 months or more	144	98
Gross unrealized losses, total	SFr 150	SFr 156

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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