Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 4,313
Operating cash flows from finance leases	35
Financing cash flows from finance leases	1,443	$ 306	$ 47
ROU assets obtained in exchange for lease obligations:
Operating leases	1,525
Finance leases	$ 15