Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended				12 Months Ended
	Feb. 23, 2021	Jan. 31, 2021	Mar. 31, 2020	May 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Subsequent events
Payment of call premium					$ 9,445	$ 0	$ 0
Payment of accrued and unpaid interest					285,600	275,300	251,500
Proceeds from common stock offerings, net					$ 728,883	$ 845,061	$ 0
Common stock | Underwritten Public Offering
Subsequent events
Proceeds from common stock offerings, net			$ 728,900	$ 845,400
Shares of common stock issued (in shares)			9,690,500	12,650,000			0
Common stock | Underwriter Option
Subsequent events
Shares of common stock issued (in shares)			690,500
3.250% notes due in October 2022 | Notes payable
Subsequent events
Interest rate (as a percent)					3.25%
Subsequent event
Subsequent events
Common stock, dividends declared (in dollars per share)	$ 0.2345	$ 0.2345
Subsequent event | Common stock | Underwritten Public Offering
Subsequent events
Proceeds from common stock offerings, net		$ 669,600
Shares of common stock issued (in shares)		12,075,000
Subsequent event | Common stock | Underwriter Option
Subsequent events
Shares of common stock issued (in shares)		1,575,000
Subsequent event | 3.250% notes due in October 2022 | Notes payable
Subsequent events
Interest rate (as a percent)		3.25%
Debt redemption price		$ 1,004,000
Early repayment of notes payable		950,000
Payment of call premium		47,200
Payment of accrued and unpaid interest		$ 7,100