Leases - Maturities of lease liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019
Operating Leases
2019	$ 2,504
2020	4,944
2021	4,864
2022	4,929
2023	4,901
2024	4,968
Thereafter	11,269
Total lease payments	38,379
Less: Interest	(11,214)
Present value of lease liabilities	27,165
Finance Leases
2019	21
2020	41
2021	41
2022	41
2023	41
2024	0
Thereafter	0
Total lease payments	185
Less: Interest	(17)
Present value of lease liabilities	168
2019	2,525
2020	4,985
2021	4,905
2022	4,970
2023	4,942
2024	4,968
Thereafter	11,269
Total lease payments	38,564
Less: Interest	(11,231)
Present value of lease liabilities	$ 27,333	$ 27,800