Related Party Transactions (Affiliated Asset Transfers) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Related Party Transaction [Line Items]
Realized investment (gains) losses, net	$ (757,691)	$ (1,342,219)
Affiliated Entity | Prudential Insurance January 2019 Sale
Related Party Transaction [Line Items]
Fair Value	20,504
Book Value	20,781
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	(277)
Affiliated Entity | Prudential Insurance February 2019 Sale
Related Party Transaction [Line Items]
Fair Value	97,953
Book Value	98,506
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	(554)
Affiliated Entity | Prudential Insurance March 2019 Purchase
Related Party Transaction [Line Items]
Fair Value	141,476
Book Value	141,476
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	7,776
Affiliated Entity | Prudential Insurance April 2019 Purchase
Related Party Transaction [Line Items]
Fair Value	4,300
Book Value	4,300
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	0
Affiliated Entity | Prudential Retirement Insurance & Annuity April 2019 Purchase
Related Party Transaction [Line Items]
Fair Value	1,258
Book Value	1,258
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	0
Affiliated Entity | Pruco Life April 2019 Purchase
Related Party Transaction [Line Items]
Fair Value	14,525
Book Value	14,525
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	0
Affiliated Entity | Prudential Insurance June 2019 - Transfer Out
Related Party Transaction [Line Items]
Fair Value	23,066
Book Value	23,002
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	64
Affiliated Entity | Prudential Insurance June 2019 - Transfer In
Related Party Transaction [Line Items]
Fair Value	19,919
Book Value	19,919
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	0
Affiliated Entity | Prudential Insurance August 2019 - Sale
Related Party Transaction [Line Items]
Fair Value	66,346
Book Value	64,735
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	1,611
Affiliated Entity | Prudential Insurance August 2019 - Sale
Related Party Transaction [Line Items]
Fair Value	106,307
Book Value	104,733
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	1,574
Affiliated Entity | Prudential Insurance November 2019 Sale
Related Party Transaction [Line Items]
Fair Value	2,289
Book Value	2,362
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	(73)
Affiliated Entity | Prudential Insurance November 2019 Sale
Related Party Transaction [Line Items]
Fair Value	6,517
Book Value	8,550
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	(2,033)
Affiliated Entity | Prudential Insurance December 2019 Purchase
Related Party Transaction [Line Items]
Fair Value	5,271
Book Value	5,271
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	0
Affiliated Entity | Prudential Insurance December 2019 Purchase
Related Party Transaction [Line Items]
Fair Value	85,261
Book Value	85,261
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	0
Affiliated Entity | Prudential Insurance December 2019 Sale
Related Party Transaction [Line Items]
Fair Value	21,425
Book Value	20,628
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	797
Affiliated Entity | Prudential International Insurance Service Company March 2020 - Purchase
Related Party Transaction [Line Items]
Fair Value	107,014
Book Value	107,014
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	0
Affiliated Entity | Prudential Insurance March 2020 Purchase
Related Party Transaction [Line Items]
Fair Value	258,885
Book Value	258,885
APIC, Net of Tax Increase/(Decrease)	0
Realized investment (gains) losses, net	$ 0