Leases - Components of lease expenses (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Finance lease cost:
Amortization of assets	$ 3,535
Interest on lease liabilities	1,693
Operating lease expense:
Operating lease cost	9,102
Variable lease cost	1,109
Sublease income	(187)
Total lease costs	$ 15,252