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Fair Value Determination, Percentage of Fixed Maturity Securities, Priced by Third Party Pricing Services

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Represents the fair value of financial instruments that are valued using broker quotes.

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Actuarially determined death rate of policyholders, which is included in determining the amount of the specified guaranteed benefit obligation as of the balance sheet date, as a percentage of the 94 GMDB table.

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Represent the payments triggered under the agreement.

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Represents the percentage of derivatives based upon notional values, excluding embedded derivatives that were priced using exchange prices or independent broker quotations.

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Represents the minimum percentage of the underlying collateral guaranteed by a third party.

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No definition available.

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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 elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value, before effects of master netting arrangements, of a financial liability or 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 liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Fair value of financial instrument classified as a 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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Federal Home Loan Bank (FHLB) stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity).

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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Amount of accrued obligation to policyholders that relates to insured events for long-duration contracts.

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FAIR VALUE OF FINANCIAL INSTRUMENTS - Additional Information (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Jun. 30, 2017	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Determination of fair values
Percentage of the Company's fixed maturity securities priced by third party pricing services	91.00%
Underlying collateral, Percentage guaranteed by the Federal Family Education Loan Program	97.00%	97.00%
Percentage of derivatives excluding embedded derivatives that were priced using exchange prices or independent broker quotations	81.20%
Fair Value, Assets	$ 441,393,000	$ 417,769,000
Fair Value, Liabilities	230,082,000	176,979,000
Interest support, YRT premium support and portfolio maintenance agreement
Determination of fair values
Fair Value, Assets	83,500,000
Golden Gate II \| Interest Support Agreement
Determination of fair values
Fair Value, Assets	37,400,000
Payments made under agreement	0
Amount of collateralized support agreement obligations by PLC	2,800,000
Golden Gate II \| YRT premium support agreement
Determination of fair values
Fair Value, Assets	41,800,000
Payments made under agreement	0
Golden Gate V and West Coast Life \| Portfolio maintenance agreements
Determination of fair values
Fair Value, Assets	4,400,000
Payments made under agreement	0
Level 3
Determination of fair values
Financial instruments valued in broker quotes	50,200,000	125,200,000
Level 3 fair value	646,324,000	493,419,000	$ 618,857,000	$ 693,684,000	$ 669,866,000	$ 468,360,000
Level 3 \| Annuity account
Determination of fair values
Level 3 fair value	85,000,000
Asset-backed securities \| Level 2
Determination of fair values
Fair Value	5,200,000,000
Asset-backed securities \| Level 3
Determination of fair values
Fair Value	588,600,000
Other asset-backed securities \| Level 3
Determination of fair values
Financial instruments valued in broker quotes	$ 35,600,000	$ 93,900,000
Underlying collateral, Percentage guaranteed by the Federal Family Education Loan Program	97.00%
Other asset-backed securities \| Level 3 \| Available-for-sale securities
Determination of fair values
Fair Value	$ 553,100,000
Other asset-backed securities \| Level 3 \| Trading securities
Determination of fair values
Fair Value	35,500,000
Corporate securities \| Level 2
Determination of fair values
Fair Value	33,000,000,000
Corporate securities \| Level 3
Determination of fair values
Fair Value	630,100,000
Equity securities
Determination of fair values
Fair Value	65,500,000
Federal Home Loan Bank stock	65,500,000
Equity securities \| Level 3
Determination of fair values
Financial instruments valued in broker quotes	$ 500,000
Embedded derivative - GLWB \| Level 3 \| Minimum
Determination of fair values
Mortality (as a percent)	91.10%
Embedded derivative - GLWB \| Level 3 \| Maximum
Determination of fair values
Mortality (as a percent)	107.00%
Embedded derivative - FIA \| Level 3 \| Minimum
Determination of fair values
Mortality (as a percent)	46.00%
Embedded derivative - FIA \| Level 3 \| Maximum
Determination of fair values
Mortality (as a percent)	113.00%
Embedded derivative - IUL \| Level 3 \| Minimum
Determination of fair values
Mortality (as a percent)	34.00%
Embedded derivative - IUL \| Level 3 \| Maximum
Determination of fair values
Mortality (as a percent)	152.00%
Embedded derivative - Modified coinsurance agreements
Determination of fair values
Statutory policy liabilities (net of policy loans)	$ 2,400,000,000
Embedded derivative - Modified coinsurance agreements \| Trading securities
Determination of fair values
Fair Value	218,800,000
Funds withheld derivative \| Level 2
Determination of fair values
Fair Value, Liabilities	$ 50,500,000