ACCOUNTING POLICIES - Schedule of VIEs (Details) - Variable Interest Entity - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
NHP/PMB L.P.
Variable Interest Entity
Total assets	$ 681,617	$ 673,467
Total liabilities	251,640	238,147
Other Identified VIEs
Variable Interest Entity
Total assets	2,121,897	2,075,499
Total liabilities	440,507	402,478
Tax Credit VIEs
Variable Interest Entity
Total assets	803,087	797,077
Total liabilities	$ 316,818	$ 298,154