Leases - Supplemental Cash flow Information to operating leases (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Supplemental cash flow information
Cash paid for amounts included in the measurement of operating lease liabilities	$ 6,356
Operating ROU assets obtained in exchange for lease liabilities	855
Supplemental balance sheet information
Operating lease ROU assets	41,317	$ 0
Operating lease liabilities:
Accrued expenses and other current liabilities	6,961
Operating lease liabilities	35,662	$ 0
Total operating lease liabilities	$ 42,623