Issuances of Common Stock - Issuance of Common Stock in Underwritten Public Offering (Details) - USD ($)	1 Months Ended			6 Months Ended
	Jul. 31, 2021	Jan. 31, 2021	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Class of Stock [Line Items]
Proceeds from share issuances, net		$ 669,600,000	$ 728,500,000	$ 669,295,000	$ 728,883,000
Commercial paper program				$ 1,000,000,000.0
Subsequent event
Class of Stock [Line Items]
Proceeds from share issuances, net	$ 594,100,000
Underwritten Public Offering
Class of Stock [Line Items]
Underwriting discounts		$ 19,300,000	$ 21,500,000
Underwritten Public Offering | Subsequent event
Class of Stock [Line Items]
Underwriting discounts	$ 2,900,000
Common stock | Underwritten Public Offering
Class of Stock [Line Items]
Shares of common stock issued (in shares)		12,075,000	9,690,500
Common stock | Underwritten Public Offering | Subsequent event
Class of Stock [Line Items]
Shares of common stock issued (in shares)	9,200,000
Common stock | Underwriter Option
Class of Stock [Line Items]
Shares of common stock issued (in shares)		1,575,000	690,500
Common stock | Underwriter Option | Subsequent event
Class of Stock [Line Items]
Shares of common stock issued (in shares)	1,200,000