Stockholders' Equity (Details) $ / shares in Units, $ in Millions	Feb. 27, 2018 $ / shares shares	Jan. 30, 2018	Jan. 26, 2018 USD ($) $ / shares shares	Dec. 31, 2018 class shares	Sep. 30, 2018 USD ($)	Dec. 31, 2017 shares
Conversion of Stock [Line Items]
Number of classes of common stock | class				2
Stockholders' Equity Note, Stock Split, Conversion Ratio		1.5543
Issuance of common stock (in shares)	1,537,500		10,250,000
Shares Issued, Price Per Share | $ / shares	$ 16.00		$ 16.00
Proceeds from Issuance Initial Public Offering | $			$ 171.5
Common stock, shares issued (in shares)				35,353,296		23,208,076
Long-term liability from the proceeds from the sale of the Class B Shares | $					$ 1.3
Management [Member]
Conversion of Stock [Line Items]
Common stock, shares issued (in shares)			170,712