DEBT AND OTHER OBLIGATIONS - Amount of Collateral Pledged for Repurchase Agreements and Securities Lending Transactions, Grouped by Asset Class (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Repurchase agreements and repurchase-to-maturity transactions	$ 62,611	$ 451,895
Securities lending transactions	75,071	72,176
Total securities	137,682	524,071
Overnight and Continuous
Debt Instrument [Line Items]
Repurchase agreements and repurchase-to-maturity transactions	62,611	433,182
Securities lending transactions	75,071	72,176
Total securities	137,682	505,358
Up to 30 days
Debt Instrument [Line Items]
Repurchase agreements and repurchase-to-maturity transactions	0	18,713
Securities lending transactions	0	0
Total securities	0	18,713
30-90 days
Debt Instrument [Line Items]
Repurchase agreements and repurchase-to-maturity transactions	0	0
Securities lending transactions	0	0
Total securities	0	0
Greater Than 90 days
Debt Instrument [Line Items]
Repurchase agreements and repurchase-to-maturity transactions	0	0
Securities lending transactions	0	0
Total securities	0	0
U.S. Treasury and agency securities
Debt Instrument [Line Items]
Repurchase agreements and repurchase-to-maturity transactions	62,611	451,895
U.S. Treasury and agency securities \| Overnight and Continuous
Debt Instrument [Line Items]
Repurchase agreements and repurchase-to-maturity transactions	62,611	433,182
U.S. Treasury and agency securities \| Up to 30 days
Debt Instrument [Line Items]
Repurchase agreements and repurchase-to-maturity transactions	0	18,713
U.S. Treasury and agency securities \| 30-90 days
Debt Instrument [Line Items]
Repurchase agreements and repurchase-to-maturity transactions	0	0
U.S. Treasury and agency securities \| Greater Than 90 days
Debt Instrument [Line Items]
Repurchase agreements and repurchase-to-maturity transactions	0	0
Corporate securities
Debt Instrument [Line Items]
Securities lending transactions	57,941
Corporate securities \| Overnight and Continuous
Debt Instrument [Line Items]
Securities lending transactions	57,941
Corporate securities \| Up to 30 days
Debt Instrument [Line Items]
Securities lending transactions	0
Corporate securities \| 30-90 days
Debt Instrument [Line Items]
Securities lending transactions	0
Corporate securities \| Greater Than 90 days
Debt Instrument [Line Items]
Securities lending transactions	0
Fixed maturities
Debt Instrument [Line Items]
Securities lending transactions		71,285
Fixed maturities \| Overnight and Continuous
Debt Instrument [Line Items]
Securities lending transactions		71,285
Fixed maturities \| Up to 30 days
Debt Instrument [Line Items]
Securities lending transactions		0
Fixed maturities \| 30-90 days
Debt Instrument [Line Items]
Securities lending transactions		0
Fixed maturities \| Greater Than 90 days
Debt Instrument [Line Items]
Securities lending transactions		0
Equity securities
Debt Instrument [Line Items]
Securities lending transactions	14,642	891
Equity securities \| Overnight and Continuous
Debt Instrument [Line Items]
Securities lending transactions	14,642	891
Equity securities \| Up to 30 days
Debt Instrument [Line Items]
Securities lending transactions	0	0
Equity securities \| 30-90 days
Debt Instrument [Line Items]
Securities lending transactions	0	0
Equity securities \| Greater Than 90 days
Debt Instrument [Line Items]
Securities lending transactions	0	$ 0
Other government related securities
Debt Instrument [Line Items]
Securities lending transactions	2,488
Other government related securities \| Overnight and Continuous
Debt Instrument [Line Items]
Securities lending transactions	2,488
Other government related securities \| Up to 30 days
Debt Instrument [Line Items]
Securities lending transactions	0
Other government related securities \| 30-90 days
Debt Instrument [Line Items]
Securities lending transactions	0
Other government related securities \| Greater Than 90 days
Debt Instrument [Line Items]
Securities lending transactions	$ 0

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No definition available.

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- Definition

Amount, before effects of master netting arrangements, of funds outstanding borrowed in the form of a financial asset repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same financial asset at a date certain for a specified price. Includes repurchase-to-maturity transactions and liabilities not subject to a master netting arrangement.

+ References

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- Definition

Amount, before effects of master netting arrangements, of financial assets loaned to entities in exchange for collateral and funds outstanding borrowed in the form of a financial asset repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same financial assets at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 7
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL34722452-111729

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 7
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL34722452-111729

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- Definition

Amount, before effects of master netting arrangements, of financial assets loaned to entities in exchange for collateral. Includes liabilities not subject to a master netting arrangement and financial assets transferred other than securities that qualify as secured borrowings.

+ References

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