Available-for-sale securities - Narrative (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) position	Dec. 31, 2021 USD ($) position
Debt Securities, Available-for-Sale [Line Items]
Number of unrealized loss positions | position	46	32
Number of available-for-sale securities | position	47	39
Unrealized holding losses depreciation percentage from amortized cost	20.30%	2.70%
Other-than-temporary impairment loss, debt securities, available-for-sale | $	$ 0
Asset Pledged as Collateral | Debt Securities
Debt Securities, Available-for-Sale [Line Items]
Financial instruments, owned, at fair value | $	$ 30,800,000	$ 36,600,000