Issuances of Common Stock - Issuance of Common Stock in Underwritten Public Offering (Details) - USD ($)	1 Months Ended			9 Months Ended
	Jul. 31, 2021	Jan. 31, 2021	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Class of Stock [Line Items]
Proceeds from share issuances, net	$ 594,100,000	$ 669,600,000	$ 728,900,000	$ 1,263,235,000	$ 728,883,000
Commercial paper program	1,000,000,000			$ 1,000,000,000
Underwritten Public Offering
Class of Stock [Line Items]
Underwriting discounts	$ 2,900,000	$ 19,300,000	$ 21,200,000
Common stock | Underwritten Public Offering
Class of Stock [Line Items]
Shares of common stock issued (in shares)	9,200,000	12,075,000	9,690,500
Common stock | Underwriter Option
Class of Stock [Line Items]
Shares of common stock issued (in shares)	1,200,000	1,575,000	690,500