Leases - Components of Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Leases [Abstract]
Operating lease cost	$ 4,172	$ 8,398
Sublease (income)	(146)	(292)
Net lease cost	$ 4,026	$ 8,106