Related Party Transactions (Narrative) (Details)		3 Months Ended
		Mar. 31, 2018 USD ($) policy	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)
Related Party Transaction [Line Items]
Other invested assets	[1]	$ 304,417,000	$ 263,074,000
Net investment income		77,915,000			$ 89,615,000
Prudential Insurance
Related Party Transaction [Line Items]
Proceeds from Contributions from Affiliates		6,000,000		$ 149,000,000	5,000,000
Dividends		0	250,000,000
Prudential Insurance
Related Party Transaction [Line Items]
Stock option program plan expense		200,000			100,000
Deferred compensation program expense		2,000,000			3,000,000
Pension plan expense		6,000,000			6,000,000
Welfare plan expense		$ 7,000,000			7,000,000
Defined contribution plan, employer matching contribution, percent (up to)		4.00%
Defined contribution plan, cost recognized		$ 3,000,000			3,000,000
Number of Corporate Owned Life Insurance policies sold | policy		5
Prudential Insurance and Prudential Financial
Related Party Transaction [Line Items]
Life Insurance, Corporate or Bank Owned, amount		$ 3,739,000,000	3,688,000,000
Fees related to Life Insurance, Corporate or Bank Owned, amount		12,000,000			12,000,000
Maximum amount of mortality risk		3,500,000
Prudential Financial
Related Party Transaction [Line Items]
Company's share of corporate expenses		$ 18,000,000			17,000,000
Number of Corporate Owned Life Insurance policies sold | policy		1
Affiliated Entity
Related Party Transaction [Line Items]
Accrued interest receivable related to long-tern notes receivable		$ 700,000	1,000,000
Revenues related to long-term notes receivable		1,000,000			1,000,000
Line of credit facility, maximum borrowing capacity		2,200,000,000.0
Interest expense related to loans payable		100,000			200,000
Affiliated Entity | PAD
Related Party Transaction [Line Items]
Commissions and fees		175,000,000			155,000,000
Affiliated Entity | ASTISI and PGIM Investments
Related Party Transaction [Line Items]
Fee income from revenue sharing agreement		84,000,000			77,000,000
Affiliated Entity | PGIM Investments
Related Party Transaction [Line Items]
Fee income from revenue sharing agreement		2,000,000			3,000,000
Affiliated Entity | PGIM
Related Party Transaction [Line Items]
Net investment income		3,000,000			3,000,000
Prudential Financial Joint Ventures
Related Party Transaction [Line Items]
Other invested assets		81,000,000	$ 79,000,000
Net investment income		$ 100,000			$ 4,000,000

[1] Prior period amounts have been reclassified to conform to current period presentation. See "Adoption of ASU 2016-01" in Note 2 for details