CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - Unaudited (Parenthetical) - $ / shares	3 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019
Stockholders' Equity Attributable to Parent
Common dividends declared - per share (in dollars per share)	$ 0.79	$ 0.75	$ 0.75	$ 0.75	$ 0.72	$ 0.72
Issuance of shares of common stock, common stock offering, net of expenses	238,086	243,621	105,837	849,751	790,052	232,205
Issuance of shares of common stock, dividend reinvestment plan	0	0	0	441	479	571
Withheld shares of common stock to satisfy tax withholding obligations in connection with the vesting of restricted stock	0	0	33,963	0	0	28,955