FAIR VALUE (Activity for Assets and Liabilities Measured on Recurring Level 3 Basis) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Reclassification of net fair value gains on sold/redeemed bonds	$ 3,571	$ 0
Net unrealized gains (losses) arising during the period	406	(3,347)
ASU 2017-08
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	(300)
Investments in Debt Securities
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Reclassification of net fair value gains on sold/redeemed bonds	3,600
Net unrealized gains (losses) arising during the period	400
Level 3 \| Derivative Liabilities
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning period		(46)
Net (losses) gains included in earnings		(2)
Balance at ending period		(48)
Level 3 \| Investments in Debt Securities
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at start of period	97,190	143,604
Net (losses) gain included in earnings		(6)
Net change in AOCI (1)	(3,165)	(3,482)
Impact from deconsolidation		17,997
Impacts from sales/redemptions	(12,590)
Impacts from settlements	(333)	(289)
Balance at end of period	81,102	157,824
Net unrealized gains (losses) arising during the period		3,400
Reclassification of realized losses (gains) to the Consolidated Statements of Operations related to bond investments assessed as other-than-temporary-impairment ("OTTI")		100
Level 3 \| Derivative Assets
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning period	1,130
Balance at start of period		2,347
Net (losses) gains included in earnings	(152)
Net (losses) gain included in earnings		(97)
Impact from settlements	(202)
Balance at ending period	$ 776
Balance at end of period		$ 2,250

Fair Value, Measurement with Unobservable Inputs Reconciliation, Increase (Decrease) from Deconsolidation

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Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of gain (loss) recognized in the income statement of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlements of financial instrument classified as a derivative asset (liability) after deduction of derivative liability, measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount before tax of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.

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Amount before tax and reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities.

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