Leases - Minimum lease payments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Minimum lease payments
2020	$ 10,540
2021	7,574
2022	7,186
2023	7,390
2024	7,601
Thereafter	22,058
Payments due	62,349
Less: imputed interest	(14,942)
Operating lease liability	$ 47,407
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019		$ 5,458
2020		7,141
2021		7,168
2022		6,820
2023		7,024
Thereafter		27,777
Total		$ 61,388

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

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

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Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments for operating lease.

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Present value of lessee's discounted obligation for lease payments from operating lease.

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Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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