CONSOLIDATED STATEMENTS OF EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common stock dividends declared and paid (in dollars per share)	$ 2.03	$ 1.95	$ 1.86
Issuance of common stock - Director compensation (in shares)	28,287	40,371	35,456
Issuance of common stock - Stock purchase plan (in shares)	6,986	10,101	13,695
Issuance of common stock - ATM equity program (in shares)	2,344,022	7,378,163	5,821,366
Issuance of common stock - Equity offering (in shares)	7,000,000
Issuance of common stock - restricted shares, net (in shares)	359,650	221,484	274,102
Series D Depositary Share
Preferred stock dividends declared and paid (in dollars per share)			$ 0.312847
Redemption of depositary shares (in shares)			11,500,000
Series E Preferred Stock
Preferred stock dividends declared and paid (in dollars per share)	$ 1.47917	$ 1.42500	$ 1.42500
Redemption of depositary shares (in shares)	11,500,000
Series F Preferred Stock
Preferred stock dividends declared and paid (in dollars per share)	$ 1.30000	$ 1.30000	$ 1.30000