Allowance for credit losses - T D R that subsequently defaulted (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) loans	Sep. 30, 2020 USD ($) loans	Sep. 30, 2021 USD ($) loans	Sep. 30, 2020 USD ($) loans
Financing Receivable
Loan count | loans	56	160	179	605
Recorded investment as of first default date | $	$ 3,246	$ 3,481	$ 21,907	$ 28,856
Mortgages
Financing Receivable
Loan count | loans	25	23	72	215
Recorded investment as of first default date | $	$ 2,503	$ 2,321	$ 7,514	$ 22,518
Commercial | CRE non-owner occupied
Financing Receivable
Loan count | loans	0	0	4	1
Recorded investment as of first default date | $	$ 0	$ 0	$ 8,421	$ 1,700
Commercial | CRE owner occupied
Financing Receivable
Loan count | loans	1	0	3	5
Recorded investment as of first default date | $	$ 383	$ 0	$ 4,138	$ 846
Commercial | Commercial and Industrial
Financing Receivable
Loan count | loans	0	0	5	3
Recorded investment as of first default date | $	$ 0	$ 0	$ 317	$ 97
Consumer | Credit card
Financing Receivable
Loan count | loans	17	124	74	290
Recorded investment as of first default date | $	$ 202	$ 975	$ 914	$ 2,190
Consumer | Personal loans
Financing Receivable
Loan count | loans	13	13	21	89
Recorded investment as of first default date | $	$ 158	$ 185	$ 603	$ 1,504
Consumer | Other
Financing Receivable
Loan count | loans		0		2
Recorded investment as of first default date | $		$ 0		$ 1