DERIVATIVE INSTRUMENTS - BALANCE SHEET OFFSETTING (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Cash collateral
Cash collateral in margin accounts	$ 4.9	$ 16.1
Offsetting Derivative Assets
Gross amount recognized on the balance sheet	3.5	2.3
Gross amount not offset on the balance sheet	(1.1)	0.0
Net amount	2.4	2.3
Offsetting Derivative Liabilities
Gross amount recognized on balance sheet	2.8	1.4
Gross amount not offset on balance sheet	(2.3)	0.0
Net amount	0.5	$ 1.4
Collateral posted	$ 1.2

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and elected not to be offset.

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Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, and obligation to return cash collateral under master netting arrangements.

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