Issuances of Common Stock - Issuance of Common Stock in Underwritten Public Offering (Details) - USD ($) $ in Thousands	1 Months Ended		9 Months Ended
	Mar. 31, 2020	May 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Class of Stock [Line Items]
Proceeds from share issuances, net			$ 728,883	$ 845,061
Common stock | Underwritten Public Offering
Class of Stock [Line Items]
Shares of common stock issued (in shares)	9,690,500	12,650,000
Underwriting discounts and other offering costs	$ 21,200	$ 31,000
Proceeds from share issuances, net	$ 728,900	$ 845,100
Common stock | Underwriter Option
Class of Stock [Line Items]
Shares of common stock issued (in shares)	690,500