DERIVATIVES. (Details) - Non Designated Derivative Instruments [Member] - USD ($) $ in Thousands |
Sep. 30, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
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| Cash Collateral Balance [Member] | |||
| Derivative assets | $ 2,400 | $ 8,479 | $ 3,813 |
| Commodity Contracts [Member] | |||
| Derivative assets | 2,790 | 1,765 | 998 |
| Derivative liabilities | $ 3,619 | $ 6,309 | $ 2,307 |
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- Definition Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as an asset. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as a liability. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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