Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions |
12 Months Ended | |||
|---|---|---|---|---|
Oct. 02, 2017 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Initial Public Offering | Class A Common Stock | ||||
| Issuance costs in connection with issuance of common stock | $ 3.1 | $ 3.1 | $ 3.1 | $ 3.1 |