SIGNIFICANT ACCOUNTING POLICIES (Details 1) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Document Fiscal Year Focus	2017
Federal Income Tax Treatment of Share Distributions [Abstract]
Ordinary taxable income distribution requirement	90.00%
Common Stock
Federal Income Tax Treatment of Share Distributions [Abstract]
Ordinary dividends (in dollars per share)	$ 2.49146	$ 2.10494	$ 2.24258
Nondividend distributions (in dollars per share)	0.02686	0.05202	0.02774
Unrecaptured Section 1250 capital gain (in dollars per share)	0.00000	0.12872	0.06968
Other capital gain (in dollars per share)	0.00168	0.15432	0.00000
Total Common Share Distributions	$ 2.52000	$ 2.44000	$ 2.34000