Leases - Future annual minimum lease payments and finance lease commitments (Details)	Dec. 31, 2019 USD ($)
Operating Leases
2020	$ 14,552,000
2021	12,168,000
2022	10,399,000
2023	9,751,000
2024	8,585,000
2025 and thereafter	46,016,000
Total minimum lease payments	101,471,000
Finance Lease, Liability, Payment, Due [Abstract]
2020	1,781,000
2021	1,816,000
2022	1,853,000
2023	465,000
2024	0
2025 and thereafter	0
Total minimum lease payments	$ 5,915,000

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Amount of lessee's undiscounted obligation for lease payments for finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918701-209980

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Amount of lessee's undiscounted obligation for lease payments for finance lease, due in second fiscal year following latest fiscal year.

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Amount of lessee's undiscounted obligation for lease payments for finance lease, due in remainder of fiscal year following latest fiscal year ended.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
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