Commitments and Contingencies (Schedule of Annual Minimum Operating Lease Payments) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Operating Lease, Liability	$ 3,751	$ 4,200	$ 0
Remainder of 2019	599
Operating Leases, Future Minimum Payments, Due in Two Years	1,235
Lessee, Operating Lease, Liability, Payments, Due Year Three	1,011
2021	734
Lessee, Operating Lease, Liability, Payments, Due Year Five	558
Total future lease payments	$ 4,137