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