CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Dividends declared and paid:
Common stock dividends (in dollars per share)	$ 0.520	$ 0.515	$ 1.550	$ 1.515
Issuance of common stock:
Director compensation (in shares)	8,865	6,964	25,624	21,933
Stock purchase plan (in shares)	1,908	1,716	6,214	5,872
ATM equity program (in shares)	216,373	848,474	1,634,350	2,344,022
Equity offering (in shares)		7,000,000		7,000,000
Restricted shares, net of forfeitures (in shares)		100,000	263,406	359,650
Common stock dividends declared and paid	$ (86,799)	$ (74,715)	$ (262,066)	$ (229,403)
Director compensation	269	325	865	968
Capital in Excess of Par Value
Issuance of common stock:
Common stock dividends declared and paid	3,147	9,219	4,298	16,168
Director compensation	268	325	864	968
Common Stock
Issuance of common stock:
Common stock dividends declared and paid	1	$ 1	1	$ 3
Director compensation	$ 1		$ 1
Series E Preferred Stock
Dividends declared and paid:
Preferred stock dividends (in dollars per share)		$ 0.356250		$ 1.068750
Series F Preferred Stock
Dividends declared and paid:
Preferred stock dividends (in dollars per share)	$ 0.325000	$ 0.325000	$ 0.975000	$ 0.975000