Leases - Future minimum payments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Operating lease liabilities under Topic 842
Operating leases - Remaining 2021	$ 21,007
Operating leases - 2022	24,843
Operating leases - 2023	22,657
Operating leases - 2024	21,549
Operating leases - 2025	18,605
Operating leases - later years	52,393
Operating leases - Total	161,054
Less: Imputed interest	(20,925)
Operating lease liabilities	140,129	$ 152,588
Finance lease liabilities under Topic 842
Finance leases - Remaining 2021	2,491
Finance leases - 2022	3,402
Finance leases - 2023	3,492
Finance leases - 2024	3,589
Finance leases - 2025	3,701
Finance leases - later years	8,850
Finance leases - Total	25,525
Less: imputed interest	(4,086)
Finance lease liabilities	$ 21,439	$ 22,572