Leases - Lease cost and other information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Lease Cost Components:
Amortization of ROU assets - finance leases	$ 117	$ 117
Interest on lease liabilities - finance leases	13	15
Operating lease cost (cost resulting from lease payments)	4,333	4,343
Short-term lease expense	143	135
Variable lease cost (cost excluded from lease payments)	437	648
Total lease cost	5,043	5,258
Supplemental Cash Flow and Other Information Related to Leases:
Finance lease - operating cash flows	13	15
Finance lease - financing cash flows	108	106
Operating lease - operating cash flows (fixed payments)	4,181	4,140
Operating lease - operating cash flows (net change asset/liability)	(3,303)	(3,220)
New ROU assets - operating leases	$ 12,428	$ 1,298
Weighted - average remaining lease term (years) - finance leases	6 years 2 months 1 day	7 years 1 month 28 days
Weighted - average remaining lease term (years) - Operating leases	10 years 5 months 19 days	11 years 3 months 18 days
Weighted - average discount rate - finance leases	1.70%	1.70%
Weighted - average discount rate - Operating leases	3.00%	3.30%
Maturity Analysis of Lease Liabilities:
2022 (excluding the quarter ended March 31, 2022)	$ 12,844
2023	16,367
2024	14,987
2025	13,559
2026	12,997
Thereafter	79,262
Total undiscounted cash flows	150,016
Discount on cash flows	(24,097)
Total operating lease liabilities	$ 125,919		$ 115,900