NATURE OF OPERATIONS AND ACCOUNTING POLICIES. - Hedging (Details) - Interest Rate Swap - Designated As Hedging Instrument - Cash Flow Hedging $ in Millions	Dec. 31, 2016 USD ($)
Financial instruments and fair value
Notional amount	$ 5.0
Fixed interest rate (as a percent)	3.10%

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant