SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - FAIR VALUE MEASUREMENTS (Details) - Fair Value, Measurements, Recurring [Member] $ in Thousands	Mar. 31, 2017 USD ($)
Levels of fair value measurements of financial assets:
Financial assets	$ 1,000
Fair Value, Inputs, Level 1
Levels of fair value measurements of financial assets:
Financial assets	1,000
Fair Value, Inputs, Level 2
Levels of fair value measurements of financial assets:
Financial assets	0
Fair Value, Inputs, Level 3
Levels of fair value measurements of financial assets:
Financial assets	$ 0

The aggregate fair value as of the balance sheet date of financial instruments and other positions owned by the entity including: (1) mortgages, mortgage-backed and asset backed securities; (2) US government and agency obligations; (3) state and municipal government obligations; (4) other sovereign government debt; (5) corporate obligations; (6) corporate equities; (7) principal investments; (8) derivative contracts; and (9) physical commodities. Includes both pledged and unpledged holdings.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 940
-SubTopic 320
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=35711157&loc=d3e42546-110969

Name:	us-gaap_FinancialInstrumentsOwnedAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant