Subsequent Events (Details) $ / shares in Units, $ in Thousands	1 Months Ended			6 Months Ended
	Jul. 31, 2021 USD ($) $ / shares shares	Jan. 31, 2021 USD ($) shares	Mar. 31, 2020 USD ($) shares	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jul. 31, 2021 GBP (£)
Subsequent Event [Line Items]
Proceeds from common stock offerings, net | $		$ 669,600	$ 728,500	$ 669,295	$ 728,883
Common stock | Underwritten Public Offering
Subsequent Event [Line Items]
Share issuances, net of costs (in shares)		12,075,000	9,690,500
Common stock | Underwriter Option
Subsequent Event [Line Items]
Share issuances, net of costs (in shares)		1,575,000	690,500
Notes payable
Subsequent Event [Line Items]
Weighted average remaining years until maturity				8 years 6 months
Subsequent event
Subsequent Event [Line Items]
Common stock dividend declared (in dollars per share) | $ / shares	$ 0.2355
Proceeds from common stock offerings, net | $	$ 594,100
Subsequent event | Common stock | Underwritten Public Offering
Subsequent Event [Line Items]
Share issuances, net of costs (in shares)	9,200,000
Subsequent event | Common stock | Underwriter Option
Subsequent Event [Line Items]
Share issuances, net of costs (in shares)	1,200,000
Subsequent event | 2027 Notes and 2033 Notes | Notes payable
Subsequent Event [Line Items]
Effective yield (as a percent)						1.48%
Weighted average remaining years until maturity	8 years 9 months 18 days
Subsequent event | 1.125% notes, issued in July 2021 and due in 2027 | Notes payable
Subsequent Event [Line Items]
Face amount of loan | £						£ 400,000,000
Stated interest rate (as a percent)						1.125%
Public offering price (as a percent)						99.305%
Effective yield (as a percent)						1.242%
Subsequent event | 1.750% notes, issued in July 2021 and due in 2033 | Notes payable
Subsequent Event [Line Items]
Face amount of loan | £						£ 350,000,000
Stated interest rate (as a percent)						1.75%
Public offering price (as a percent)						99.842%
Effective yield (as a percent)						1.757%