Stockholders' Equity - At-the-Market Offerings - Additional Information (Details) - At-the-Market Offerings - Class A Common Stock - USD ($) $ / shares in Units, shares in Millions, $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Mar. 31, 2019 |
Jun. 30, 2019 |
May 16, 2019 |
Mar. 12, 2019 |
|
| Class Of Stock [Line Items] | ||||
| Maximum aggregate offering price of common stock | $ 100.0 | |||
| Gross proceeds from issuance of common stock | $ 100.0 | $ 82.9 | ||
| Number of shares Issued | 1.4 | 1.0 | ||
| Average selling price per share | $ 72.00 | $ 82.90 | ||
| Stock Issuance Costs | $ 2.0 | $ 1.6 | ||
| Maximum aggregate offering shares of common stock | 1.0 |