ACCOUNTING POLICIES - Schedule of VIEs (Details) - Variable Interest Entity - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
NHP/PMB L.P.
Variable Interest Entity
Total assets	$ 589,436	$ 605,150
Total liabilities	198,163	199,958
Other Identified VIEs
Variable Interest Entity
Total assets	1,840,520	1,983,183
Total liabilities	303,440	348,124
Tax Credit VIEs
Variable Interest Entity
Total assets	801,694	988,598
Total liabilities	$ 304,234	$ 221,908