Leases - Lease cost and other information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Lease Cost Components:
Amortization of ROU assets - finance leases	$ 117	$ 117	$ 350	$ 350
Interest on lease liabilities - finance leases	10	12	31	37
Operating lease cost (cost resulting from lease payments)	4,296	4,550	12,814	13,419
Short-term lease cost	104	218	318	592
Variable lease cost (cost excluded from lease payments)	852	615	2,327	1,813
Total lease cost	5,379	5,512	15,840	16,211
Supplemental Cash Flow and Other Information Related to Leases:
Finance lease - operating cash flows	10	12	31	37
Finance lease - financing cash flows	111	109	331	325
Operating lease - operating cash flows (fixed payments)	4,233	4,356	12,483	12,982
Operating lease - operating cash flows (net change asset/liability)	$ (3,400)	$ (3,466)	(10,008)	(10,313)
New ROU assets - operating leases			$ 701	$ 12,616
Weighted - average remaining lease term (years) - finance leases	4 years 8 months 4 days	5 years 8 months 1 day	4 years 8 months 4 days	5 years 8 months 1 day
Weighted - average remaining lease term (years) - operating leases	9 years 5 months 19 days	10 years 1 month 17 days	9 years 5 months 19 days	10 years 1 month 17 days
Weighted - average discount rate - finance leases	1.70%	1.70%	1.70%	1.70%
Weighted - average discount rate - operating leases	3.10%	3.00%	3.10%	3.00%
Maturity Analysis of Lease Liabilities:
2023 (excluding 9 months ended September 30, 2023)	$ 4,187		$ 4,187
2024	15,799		15,799
2025	14,450		14,450
2026	14,058		14,058
2027	13,080		13,080
Thereafter	68,542		68,542
Total undiscounted cash flows	130,116		130,116
Discount on cash flows	(19,118)		(19,118)
Total operating lease liabilities	$ 110,998		$ 110,998		$ 115,600
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other Liabilities.		Other Liabilities.		Other Liabilities.