Leases - Supplemental cash flow information (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Leases
Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases	$ 1,685
Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from finance leases	14
Cash paid for amounts included in the measurement of lease liabilities: Financing cash flows from finance leases	58
Right-of-use assets obtained in exchange for lease obligations: Operating leases	4,369
Right-of-use assets obtained in exchange for lease obligations: Finance leases	$ 429