ACCOUNTING POLICIES - Revenue Recognition (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Revenue Recognition [Abstract]
Straight-line rent receivables	$ 210,644	$ 187,572
Straight-line rent receivable, net of allowances	$ 96,400	$ 83,500
Term of resident lease agreements, minimum	12 months
Term of resident lease agreements, maximum	18 months
Notice period to cancel lease agreements by the resident	30 days