Leases – Annual future commitments under non-cancelable leases (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Lease Obligations, Operating Leases
Remainder of 2019	$ 1,482
2020	5,911
2021	4,551
2022	4,380
2023	4,075
Thereafter	5,309
Total minimum future obligations	25,708
Less interest	(3,402)
Present value of net future minimum obligations	22,306
Less current lease obligations	(4,745)	$ (2,921)
Long-term lease obligations	17,561	7,644
Lease Obligations, Finance Leases
Remainder of 2019	440
2020	1,428
2021	735
2022	566
2023	164
Thereafter	25
Total minimum future obligations	3,358
Less interest	(241)
Present value of net future minimum obligations	3,117
Less current lease obligations	(1,238)	(1,500)
Long-term lease obligations	$ 1,879	$ 2,319	$ 2,319