FAIR VALUE OF FINANCIAL INSTRUMENTS (Details 3) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Corporate Debt Securities
Reconciliation of assets measured on Level 3 basis
Balance at the beginning of the period	$ 175,206	$ 194,986
Included in earnings	85,978	(44,882)
Transfers into Level 3	0	0
Transfers out of Level 3 (2)	0	0
Purchases	0	0
Sales	(8,956)	0
Settlements	(25,030)	(36)
Balance at the end of the period	227,198	150,068
Change in unrealized gains or losses for the period included in earnings for assets held at the end of the reporting period	84,841	(44,882)
Residential Mortgage- Backed Securities
Reconciliation of assets measured on Level 3 basis
Balance at the beginning of the period	40,663	49,621
Included in earnings	1,164	332
Transfers into Level 3	0	0
Transfers out of Level 3 (2)	0	0
Purchases	0	0
Sales	0	0
Settlements	(2,541)	(2,239)
Balance at the end of the period	39,286	47,714
Change in unrealized gains or losses for the period included in earnings for assets held at the end of the reporting period	1,164	329
Corporate Loans
Reconciliation of assets measured on Level 3 basis
Balance at the beginning of the period	129,194	298,734
Included in earnings	2,940	(6,827)
Transfers into Level 3	0	0
Transfers out of Level 3 (2)	(9,565)	0
Purchases	6,072	2,306
Sales	(332)	0
Settlements	(3,221)	2,769
Balance at the end of the period	125,088	296,982
Change in unrealized gains or losses for the period included in earnings for assets held at the end of the reporting period	2,940	(6,827)
Equity Investments, at Estimated Fair Value
Reconciliation of assets measured on Level 3 basis
Balance at the beginning of the period	132,305	146,648
Included in earnings	(1,501)	(8,085)
Transfers into Level 3	0	0
Transfers out of Level 3 (2)	0	0
Purchases	321	0
Sales	0	0
Settlements	0	0
Balance at the end of the period	131,125	138,563
Change in unrealized gains or losses for the period included in earnings for assets held at the end of the reporting period	(1,501)	(8,085)
Interests in Joint Ventures and Partnerships
Reconciliation of assets measured on Level 3 basis
Balance at the beginning of the period	793,996	888,408
Included in earnings	35,963	(80,695)
Transfers into Level 3	0	0
Transfers out of Level 3 (2)	0	0
Purchases	18,320	14,067
Sales	0	0
Settlements	(6,546)	(73,451)
Balance at the end of the period	841,733	748,329
Change in unrealized gains or losses for the period included in earnings for assets held at the end of the reporting period	35,963	(80,695)
Foreign Exchange Options, Net
Reconciliation of assets measured on Level 3 basis
Balance at the beginning of the period	992
Included in earnings	(176)
Transfers into Level 3	0
Transfers out of Level 3 (2)	0
Purchases	0
Sales	0
Settlements	0
Balance at the end of the period	816
Change in unrealized gains or losses for the period included in earnings for assets held at the end of the reporting period	(633)
Warrants
Reconciliation of assets measured on Level 3 basis
Balance at the beginning of the period	1,528	2,887
Included in earnings	171	(1,046)
Transfers into Level 3	0	0
Transfers out of Level 3 (2)	0	0
Purchases	0	0
Sales	0	0
Settlements	0	0
Balance at the end of the period	1,699	1,841
Change in unrealized gains or losses for the period included in earnings for assets held at the end of the reporting period	171	(1,046)
Options
Reconciliation of assets measured on Level 3 basis
Balance at the beginning of the period	1,001	95
Included in earnings	463	403
Transfers into Level 3	0	0
Transfers out of Level 3 (2)	0	0
Purchases	0	0
Sales	0	0
Settlements	0	0
Balance at the end of the period	1,464	498
Change in unrealized gains or losses for the period included in earnings for assets held at the end of the reporting period	$ 463	$ 403