Shareholders Equity (Details) - USD ($) $ / shares in Units, $ in Millions	Jun. 25, 2018	May 25, 2018	May 22, 2018	Mar. 31, 2019	Dec. 31, 2018
Subsidiary, Sale of Stock [Line Items]
Common stock issued	14,375,000			62,600,443	62,516,627
Common stock, par value				$ 0.0001	$ 0.0001
Net proceeds	$ 53.8
Offering
Subsidiary, Sale of Stock [Line Items]
Common stock issued		12,500,000
Common stock, par value			$ 0.0001
Public offering price			$ 4.00
Net proceeds		$ 46.7
Underwriters' option
Subsidiary, Sale of Stock [Line Items]
Common stock issued	1,875,000		1,875,000
Public offering price	$ 4.00
Purchase price			$ 3.76
Number of days to underwriters to sell additional common shares			30 days
Net proceeds	$ 7.1