Fair Value of Assets and Liabilities (Quantitative Info for Level 3 Inputs) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Fair Value Quantiative Information [Line Items]
Corporate securities	$ 6,360	$ 31,824
Fair Value, Measurements, Recurring
Fair Value Quantiative Information [Line Items]
Future policy benefits	8,529,566	5,588,840
Policyholders’ account balances	$ 962,351	13,015
Level 3 \| Minimum
Fair Value Quantiative Information [Line Items]
Fair Value Inputs, Policyholder Age	45 years
Level 3 \| Minimum \| Future policy benefits
Fair Value Quantiative Information [Line Items]
Mortality rate	0.00%
Level 3 \| Maximum
Fair Value Quantiative Information [Line Items]
Fair Value Inputs, Policyholder Age	90 years
Level 3 \| Fair Value, Measurements, Recurring
Fair Value Quantiative Information [Line Items]
Future policy benefits	$ 8,529,566	5,588,840
Policyholders’ account balances	$ 962,351	$ 13,015
Level 3 \| Internal \| Minimum \| Discounted cash flow \| Future policy benefits
Fair Value Quantiative Information [Line Items]
Lapse rate	1.00%	1.00%
Spread over LIBOR	0.10%	0.36%
Utilization rate	43.00%	50.00%
Withdrawal rate (greater than maximum range)	78.00%	78.00%
Mortality rate	0.00%	0.00%
Equity volatility curve	13.00%	18.00%
Level 3 \| Internal \| Minimum \| Discounted cash flow \| Policyholders' account balances
Fair Value Quantiative Information [Line Items]
Lapse rate	1.00%
Spread over LIBOR	0.10%
Mortality rate	0.00%
Equity volatility curve	10.00%
Level 3 \| Internal \| Minimum \| Discounted cash flow \| Corporate securities
Fair Value Quantiative Information [Line Items]
Discount rate	5.24%	7.00%
Level 3 \| Internal \| Minimum \| Market comparables \| Corporate securities
Fair Value Quantiative Information [Line Items]
EBITDA multiples	5.7
Level 3 \| Internal \| Minimum \| Liquidation \| Corporate securities
Fair Value Quantiative Information [Line Items]
Liquidation value		40.71%
Level 3 \| Internal \| Maximum \| Discounted cash flow \| Future policy benefits
Fair Value Quantiative Information [Line Items]
Lapse rate	18.00%	13.00%
Spread over LIBOR	1.23%	1.60%
Utilization rate	97.00%	97.00%
Withdrawal rate (greater than maximum range)	100.00%	100.00%
Mortality rate	15.00%	15.00%
Equity volatility curve	23.00%	22.00%
Level 3 \| Internal \| Maximum \| Discounted cash flow \| Policyholders' account balances
Fair Value Quantiative Information [Line Items]
Lapse rate	6.00%
Spread over LIBOR	1.23%
Mortality rate	24.00%
Equity volatility curve	23.00%
Level 3 \| Internal \| Maximum \| Discounted cash flow \| Corporate securities
Fair Value Quantiative Information [Line Items]
Discount rate	17.47%	20.00%
Level 3 \| Internal \| Maximum \| Market comparables \| Corporate securities
Fair Value Quantiative Information [Line Items]
EBITDA multiples	5.7
Level 3 \| Internal \| Maximum \| Liquidation \| Corporate securities
Fair Value Quantiative Information [Line Items]
Liquidation value		40.71%
Level 3 \| Internal \| Weighted Average \| Discounted cash flow \| Corporate securities
Fair Value Quantiative Information [Line Items]
Discount rate	8.25%	10.21%
Level 3 \| Internal \| Weighted Average \| Market comparables \| Corporate securities
Fair Value Quantiative Information [Line Items]
EBITDA multiples	5.7
Level 3 \| Internal \| Weighted Average \| Liquidation \| Corporate securities
Fair Value Quantiative Information [Line Items]
Liquidation value		40.71%
Level 3 \| Internal \| Fair Value, Measurements, Recurring \| Future policy benefits
Fair Value Quantiative Information [Line Items]
Future policy benefits	$ 8,529,566	$ 5,588,840
Level 3 \| Internal \| Fair Value, Measurements, Recurring \| Policyholders' account balances
Fair Value Quantiative Information [Line Items]
Policyholders’ account balances	962,351
Level 3 \| Internal \| Fair Value, Measurements, Recurring \| Corporate securities
Fair Value Quantiative Information [Line Items]
Corporate securities	27,816	31,503
Level 3 \| Internal \| Fair Value, Measurements, Recurring \| Reinsurance recoverables
Fair Value Quantiative Information [Line Items]
Reinsurance recoverables	$ 8,539,671	$ 5,600,008

Fair Value Inputs Discount Rates

No definition available.

Name:	cik777917_FairValueInputsDiscountRates
Namespace Prefix:	cik777917_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Market valuation of entity divided by earnings before interest, taxes, depreciation, and amortization (EBITDA), used as an input to measure fair value.

+ References

No definition available.

+ Details

Name:	cik777917_FairValueInputsEarningsBeforeInterestTaxesDepreciationAndAmortizationMultiples
Namespace Prefix:	cik777917_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair Value Inputs Equity Volatility Curve

+ References

No definition available.

+ Details

Name:	cik777917_FairValueInputsEquityVolatilityCurve
Namespace Prefix:	cik777917_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Actuarially determined assumption around contract lapse rates used as in input in calculating fair value of future policy benefits (primarily embedded derivatives associated with living benefit features on annuity contracts.

+ References

No definition available.

+ Details

Name:	cik777917_FairValueInputsLapseRate
Namespace Prefix:	cik777917_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Liquidation value of asset or liability used as an input to a fair value calculation.

+ References

No definition available.

+ Details

Name:	cik777917_FairValueInputsLiquidationValue
Namespace Prefix:	cik777917_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Actuarially determined assumption around client mortality rates used as in input in calculating fair value of future policy benefits (primarily embedded derivatives associated with living benefit features on annuity contracts.

+ References

No definition available.

+ Details

Name:	cik777917_FairValueInputsMortalityRate
Namespace Prefix:	cik777917_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair Value Inputs, Policyholder Age

+ References

No definition available.

+ Details

Name:	cik777917_FairValueInputsPolicyholderAge
Namespace Prefix:	cik777917_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair Value Inputs Spread Over Libor

+ References

No definition available.

+ Details

Name:	cik777917_FairValueInputsSpreadOverLibor
Namespace Prefix:	cik777917_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Actuarially determined assumption around utilization rates used as in input in calculating fair value of future policy benefits (primarily embedded derivatives associated with living benefit features on annuity contracts.

+ References

No definition available.

+ Details

Name:	cik777917_FairValueInputsUtilizationRate
Namespace Prefix:	cik777917_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Actuarially determined assumption around withdrawal rates used as in input in calculating fair value of future policy benefits (primarily embedded derivatives associated with living benefit features on annuity contracts.

+ References

No definition available.

+ Details

Name:	cik777917_FairValueInputsWithdrawalRate
Namespace Prefix:	cik777917_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items for Fair Value Quantitative Information level 3 inputs

+ References

No definition available.

+ Details

Name:	cik777917_FairValueQuantiativeInformationLineItems
Namespace Prefix:	cik777917_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	cik777917_QuantitativeInfoReinsuranceRecoverables
Namespace Prefix:	cik777917_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The aggregate amount of policy reserves (provided for future obligations including unpaid claims and claims adjustment expenses) and policy benefits (liability for future policy benefits) as of the balance sheet date; grouped amount of all the liabilities associated with the company's insurance policies.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(13)(a)(1))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (cc)
-URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437

+ Details

Name:	us-gaap_LiabilityForFuturePolicyBenefitsAndUnpaidClaimsAndClaimsAdjustmentExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of investment in marketable security.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.4)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_MarketableSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount due to policyholders for funds held that are returnable under the terms of insurance contracts, classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.14)
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

+ Details

Name:	us-gaap_OtherPolicyholderFunds
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=cik777917_FuturePolicyBenefitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cik777917_PricingSourceAxis=cik777917_InternalPricingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=us-gaap_IncomeApproachValuationTechniqueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=cik777917_PolicyholdersAccountBalancesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=us-gaap_MarketApproachValuationTechniqueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=us-gaap_CostApproachValuationTechniqueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_ReinsuranceRecoverableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: