Related Party Transactions (Narrative) (Details) - USD ($)	3 Months Ended					9 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Related Party Transaction [Line Items]
Investment expense	$ 3,783,000			$ 3,787,000		$ 11,431,000	$ 7,798,000
Other long-term investments	190,020,000		$ 551,931,000			190,020,000
Net investment income	107,953,000			115,318,000		314,310,000	233,147,000
Contributed capital						0	860,573,000
Dividends						0
Prudential Insurance
Related Party Transaction [Line Items]
Stock option program plan expense	0			0		0	100,000
Deferred compensation program expense	200,000			200,000		600,000	500,000
Pension plan expense	300,000			300,000		1,000,000	900,000
Welfare plan expense	400,000			400,000		$ 1,000,000	1,000,000
Defined contribution plan employer matching contribution percent						4.00%
Defined contribution plan, cost recognized	100,000			100,000		$ 400,000	400,000
Affiliated Entity
Related Party Transaction [Line Items]
Accrued interest receivable related to long-term notes receivables	600,000		100,000			600,000
Revenue related to long-term notes receivable	200,000			200,000		500,000	700,000
Interest expense related to loans payable	19,000,000			20,000,000		48,000,000	39,000,000
Affiliated Entity | PAIST
Related Party Transaction [Line Items]
Allocated lease expense	0			100,000		0	100,000
Allocated sub-lease rental income	0			0		0	0
Affiliated Entity | PAD
Related Party Transaction [Line Items]
Commissions and fees	27,000,000			28,000,000		81,000,000	82,000,000
Affiliated Entity | ASTISI and PGIM Investments
Related Party Transaction [Line Items]
Fee income from revenue sharing agreement	28,000,000			29,000,000		83,000,000	84,000,000
Affiliated Entity | PGIM
Related Party Transaction [Line Items]
Investment expense	3,000,000			4,000,000		9,000,000	8,000,000
Prudential Financial Joint Venture
Related Party Transaction [Line Items]
Other long-term investments	109,000,000		102,000,000			109,000,000
Net investment income	2,000,000			3,000,000		7,000,000	3,000,000
Prudential Financial
Related Party Transaction [Line Items]
Company's share of corporate expenses (benefits)	(2,000,000)			$ 2,000,000		10,000,000	$ 7,000,000
Line of credit facility, maximum borrowing capacity	9,000,000,000					$ 9,000,000,000
PAI
Related Party Transaction [Line Items]
Contributed capital					$ 8,422,000,000
Return of capital	$ 200,000,000	$ 100,000,000	$ 1,140,000,000