Leases - Future minimum payments (Details) $ in Thousands	Jun. 30, 2019 USD ($)
Operating lease liabilities under Topic 842
Operating leases - Remaining 2019	$ 14,927
Operating leases - 2020	27,345
Operating leases - 2021	24,759
Operating leases - 2022	21,019
Operating leases - 2023	18,862
Operating leases - later years	72,861
Operating leases - Total	179,773
Less: Imputed interest	(27,467)
Operating lease liabilities	152,306
Finance lease liabilities under Topic 842
Finance leases - Remaining 2019	1,466
Finance leases - 2020	3,003
Finance leases - 2021	3,093
Finance leases - 2022	3,187
Finance leases - 2023	3,284
Finance leases - later years	11,186
Finance leases - Total	25,219
Less: imputed interest	(5,182)
Finance lease liabilities	$ 20,037