Related Party Transactions (Affiliated Asset Transfers) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Related Party Transaction [Line Items]
Realized investment gains (losses)	$ (49,042)	$ (32,579)
Affiliated Entity \| PALAC January 17 Purchase
Related Party Transaction [Line Items]
Fair Value	29
Book Value	29
APIC, Net of Tax Increase/(Decrease)	0
Realized investment gains (losses)	0
Affiliated Entity \| Prudential Insurance June 2017 Sale
Related Party Transaction [Line Items]
Fair Value	16,965
Book Value	16,515
APIC, Net of Tax Increase/(Decrease)	293
Realized investment gains (losses)	0
Affiliated Entity \| Prudential Insurance June 2017 Sale
Related Party Transaction [Line Items]
Fair Value	43,198
Book Value	42,301
APIC, Net of Tax Increase/(Decrease)	584
Realized investment gains (losses)	0
Affiliated Entity \| UPARC September 2017 Transfer In
Related Party Transaction [Line Items]
Fair Value	37,354
Book Value	37,354
APIC, Net of Tax Increase/(Decrease)	0
Realized investment gains (losses)	0
Affiliated Entity \| GUL Re September 2017 Transfer Out
Related Party Transaction [Line Items]
Fair Value	72,354
Book Value	72,354
APIC, Net of Tax Increase/(Decrease)	0
Realized investment gains (losses)	0
Affiliated Entity \| GUL Re September 2017 Transfer Out
Related Party Transaction [Line Items]
Fair Value	1,254,457
Book Value	1,195,697
APIC, Net of Tax Increase/(Decrease)	0
Realized investment gains (losses)	58,760
Affiliated Entity \| Prudential Financial September 2017 Transfer In
Related Party Transaction [Line Items]
Fair Value	415,271
Book Value	376,412
APIC, Net of Tax Increase/(Decrease)	25,259
Realized investment gains (losses)	0
Affiliated Entity \| Prudential Financial September 2017 Transfer Out
Related Party Transaction [Line Items]
Fair Value	415,271
Book Value	376,412
APIC, Net of Tax Increase/(Decrease)	25,259
Realized investment gains (losses)	0
Affiliated Entity \| UPARC September 2017 Transfer In
Related Party Transaction [Line Items]
Fair Value	417,067
Book Value	385,459
APIC, Net of Tax Increase/(Decrease)	0
Realized investment gains (losses)	31,608
Affiliated Entity \| UPARC September 2017 Transfer In
Related Party Transaction [Line Items]
Fair Value	6,225
Book Value	5,002
APIC, Net of Tax Increase/(Decrease)	0
Realized investment gains (losses)	1,223
Affiliated Entity \| GUL Re September 2017 Transfer Out
Related Party Transaction [Line Items]
Fair Value	6,225
Book Value	5,002
APIC, Net of Tax Increase/(Decrease)	0
Realized investment gains (losses)	1,223
Affiliated Entity \| UPARC September 2017 Purchase
Related Party Transaction [Line Items]
Fair Value	20,685
Book Value	20,685
APIC, Net of Tax Increase/(Decrease)	0
Realized investment gains (losses)	0
Affiliated Entity \| UPARC November 2017 Purchase
Related Party Transaction [Line Items]
Fair Value	41,250
Book Value	34,332
APIC, Net of Tax Increase/(Decrease)	0
Realized investment gains (losses)	6,919
Affiliated Entity \| Prudential Insurance December 2017 Sale
Related Party Transaction [Line Items]
Fair Value	106,199
Book Value	105,191
APIC, Net of Tax Increase/(Decrease)	655
Realized investment gains (losses)	0
Affiliated Entity \| DART January 2018 Purchase
Related Party Transaction [Line Items]
Fair Value	21,457
Book Value	21,457
APIC, Net of Tax Increase/(Decrease)	0
Realized investment gains (losses)	$ 0

Amortized Cost of assets associated with the Asset Transfer.

No definition available.

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

- Definition

Fair Value of assets associated with the Asset Transfer.

+ References

No definition available.

+ Details

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

- Definition

Excess of issue price over par or stated value of the entity's capital stock and amounts received from other transactions involving the entity's stock or stockholders. Includes adjustments to additional paid in capital. Some examples of such adjustments include recording the issuance of debt with a beneficial conversion feature and certain tax consequences of equity instruments awarded to employees. Use this element for the aggregate amount of additional paid-in capital associated with common and preferred stock. For additional paid-in capital associated with only common stock, use the element additional paid in capital, common stock. For additional paid-in capital associated with only preferred stock, use the element additional paid in capital, preferred stock.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(30)(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	instant

- Definition

The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.3(a))
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 325
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=75031664&loc=d3e22529-158502

+ Details

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Balance Type:	credit
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- Definition

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.

+ References

No definition available.

+ Details

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