CONSOLIDATED STATEMENTS OF CHANGES IN COMMON STOCK EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Dividends per Common Share	$ 1.44	$ 1.42	$ 1.40
Common stock, shares issued		32,095	36,265
Dividend and Distribution Reinvestment and Share Purchase Plan
Common stock, shares issued	26,256
Registered Public Offering
Common stock, shares issued	690,000