Equity (All Other Net Unrealized Investment Gains (Losses) in AOCI) (Details) $ in Thousands	9 Months Ended
Sep. 30, 2020 USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 281,442
Ending Balance	455,083
Accumulated Other Comprehensive Income (Loss) Related To Net Unrealized Investment Gains (Losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	289,359
Ending Balance	473,196
All Other \| Net Unrealized Gains (Losses) on Investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	425,180
Net investment gains (losses) on investments arising during the period	288,642
Reclassification adjustment for (gains) losses included in net income	(1,200)
Reclassification due to allowance for credit losses recorded during the period	927
Impact of net unrealized investment (gains) losses on deferred policy acquisition costs and other costs	0
Impact of net unrealized investment (gains) losses on future policy benefits and policyholders' account balances	0
Ending Balance	713,549
All Other \| Deferred Policy Acquisition Costs and Other Costs
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	423,227
Net investment gains (losses) on investments arising during the period	0
Reclassification adjustment for (gains) losses included in net income	0
Reclassification due to allowance for credit losses recorded during the period	0
Impact of net unrealized investment (gains) losses on deferred policy acquisition costs and other costs	555,395
Impact of net unrealized investment (gains) losses on future policy benefits and policyholders' account balances	0
Ending Balance	978,622
All Other \| Future Policy Benefits and Policyholders’ Account Balances
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(482,134)
Net investment gains (losses) on investments arising during the period	0
Reclassification adjustment for (gains) losses included in net income	0
Reclassification due to allowance for credit losses recorded during the period	0
Impact of net unrealized investment (gains) losses on deferred policy acquisition costs and other costs	0
Impact of net unrealized investment (gains) losses on future policy benefits and policyholders' account balances	(610,735)
Ending Balance	(1,092,869)
All Other \| Deferred Income Tax (Liability) Benefit
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(76,914)
Net investment gains (losses) on investments arising during the period	(60,616)
Reclassification adjustment for (gains) losses included in net income	252
Reclassification due to allowance for credit losses recorded during the period	(195)
Impact of net unrealized investment (gains) losses on deferred policy acquisition costs and other costs	(116,635)
Impact of net unrealized investment (gains) losses on future policy benefits and policyholders' account balances	128,254
Ending Balance	(125,854)
All Other \| Accumulated Other Comprehensive Income (Loss) Related To Net Unrealized Investment Gains (Losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	289,359
Net investment gains (losses) on investments arising during the period	228,026
Reclassification adjustment for (gains) losses included in net income	(948)
Reclassification due to allowance for credit losses recorded during the period	732
Impact of net unrealized investment (gains) losses on deferred policy acquisition costs and other costs	438,760
Impact of net unrealized investment (gains) losses on future policy benefits and policyholders' account balances	(482,481)
Ending Balance	$ 473,448

Non Credit Portion Of Allowance for Credit Losses Of Debt Reclassification Recognized In Other Comprehensive Income

No definition available.

Name:	cik777917_NonCreditPortionOfAllowanceforCreditLossesOfDebtReclassificationRecognizedInOtherComprehensiveIncome
Namespace Prefix:	cik777917_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Other Comprehensive Income for Unrealized Investment Gain Loss related to Policyholder's account balance Arising during the Period Net of Tax

+ References

No definition available.

+ Details

Name:	cik777917_OtherComprehensiveIncomeForUnrealizedInvestmentGainLossRelatedToPolicyholdersAccountBalanceArisingDuringPeriodNetOfTax
Namespace Prefix:	cik777917_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Other Comprehensive Income for Unrealized Investment (Gain) Loss related to deferred policy acquisition costs, deferred sales inducements and valuation of business acquired Arising during the Period Net of Tax

+ References

No definition available.

+ Details

Name:	cik777917_OtherComprehensiveIncomeUnrealizedInvestmentGainLossOnDeferredCostsPolicyAcquisitionAndSalesInducementsAndValuationOfBusinessAcquiredArisingDuringPeriodNetOfTax
Namespace Prefix:	cik777917_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

Name:	us-gaap_AOCIAttributableToParentNetOfTaxRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(30)(a)(4))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e637-108580

Reference 3: 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)(23)(a)(3))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669686-108580

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (h)(2)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (g)(2)(ii)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e681-108580

+ Details

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

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e689-108580

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e637-108580

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27357-111563

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 17A
-URI http://asc.fasb.org/extlink&oid=121641772&loc=SL34724391-108580

+ Details

Name:	us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, after tax and before adjustment, of unrealized holding gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Excludes unrealized gain (loss) on investment in debt security measured at amortized cost (held-to-maturity) from transfer to available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669646-108580

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e637-108580

+ Details

Name:	us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=cik777917_OtherNetUnrealizedInvestmentGainsAndLossesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementEquityComponentsAxis=cik777917_AccumulatedNetUnrealizedInvestmentGainLossPreTaxMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementEquityComponentsAxis=cik777917_DeferredCostsPolicyAcquisitionAndSalesInducementsAndValuationOfBusinessAcquiredPreTaxMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementEquityComponentsAxis=cik777917_PolicyholdersAccountBalancesPreTaxMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementEquityComponentsAxis=cik777917_DeferredIncomeTaxLiabilityBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: