Description of Operations and Summary of Significant Accounting Policies - Accounting Pronouncements (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	[1]
Recently Issued Accounting Pronouncement Not Yet Adopted
Operating lease right-of-use asset	$ 1,421		$ 0
Operating lease liability	$ 1,546
ASU 2016-02, Leases
Recently Issued Accounting Pronouncement Not Yet Adopted
Operating lease right-of-use asset		$ 1,500
Operating lease liability		$ 1,600

[1] Condensed consolidated balance sheet as of December 31, 2018 has been derived from audited consolidated financial statements.