ACCOUNTING POLICIES - Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Revenue Recognition [Abstract]
Straight-line rent receivables	$ 228,621	$ 219,064
Straight-line rent receivable, net of allowances	$ 99,900	$ 101,400
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