Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments And Contingencies Disclosure [Abstract]

Summary of Future Annual Minimum Lease Payments Due Under Non-cancellable Operating Leases

Future annual minimum lease payments due under non-cancellable operating leases at December 31 of each year are as follows (in thousands):

2018	$	355
2019		367
2020		300
2021		—
Thereafter		—
Total minimum lease payments	$	1,022