Leases - Components of Lease Expense, Lease Term and Discount Rate (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Leases [Abstract]
Operating lease cost	$ 1,182	$ 2,448
Short-term lease cost	21	42
Variable lease cost	411	454
Sublease income	(18)	(35)
Total lease cost	$ 1,596	$ 2,909
Weighted Average Remaining Lease Term	3 years 2 months 12 days	3 years 2 months 12 days
Weighted Average Discount Rate (percent)	4.10%	4.10%