Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Leases [Line Items]
Cash paid for operating lease liability	$ 0.1
ROU asset obtained in exchange for new operating lease liability	1.4
Rent expense	$ 0.1	$ 0.1
Original Operating Lease [Member]
Leases [Line Items]
Operating lease agreement, original date	2014-01
Fifth Amended Operating Lease [Member]
Leases [Line Items]
Lease expiration date	Jun. 30, 2021
Operating lease agreement, date of amendment	2017-12
Operating lease, property description	The lease was last amended in December 2017 to extend the expiration date to June 30, 2021, with an option to extend the lease for two additional years. The Company did not assume the option to extend the lease term in its determination of the lease term as the exercise of the option was not reasonable certain to exercise when the lease was last amended in December 2017.
Lessee, operating lease, existence of option to extend [true false]	true
Option to extend the lease	option to extend the lease for two additional years.
Operating lease, renewal term	2 years
Operating lease, remaining term	2 years 3 months 18 days