COMMITMENTS AND CONTINGENCIES, INCLUDING FINANCIAL INSTRUMENTS WITH OFF-BALANCE-SHEET RISK - Repurchase Agreements (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Repurchase Agreements
Outstanding funds	$ 1.5	$ 2.3

Carrying amount of assets sold under agreements to repurchase when the carrying amount (or market value, if higher than the carrying amount) of securities or other assets sold under repurchase agreements exceeds 10 percent of total assets.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(m)(1)(i)(A)(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Name:	us-gaap_AssetsSoldUnderAgreementsToRepurchaseCarryingAmounts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant