CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - Unaudited (Parenthetical) - $ / shares	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018
Stockholders' Equity Attributable to Parent
Common dividends declared - per share (in dollars per share)	$ 0.72	$ 0.72	$ 0.64	$ 0.64
Issuance of shares of common stock, common stock offering, net of expenses	790,052	232,205	750,282	179,501
Issuance of shares of common stock, dividend reinvestment plan	479	571	565	667
Withheld shares of common stock to satisfy tax withholding obligations in connection with the vesting of restricted stock	0	28,955	0	23,824