Related Party Transactions (Narrative) (Details) - USD ($)	3 Months Ended							9 Months Ended		12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Related Party Transaction [Line Items]
Investment expense	$ 6,687,000				$ 5,332,000			$ 19,865,000	$ 14,685,000
Commissions and fees	489,440,000				527,152,000			1,441,991,000	1,559,874,000
Other invested assets	600,610,000			$ 474,013,000				600,610,000		$ 474,013,000
Net investment income	144,669,000				149,367,000			426,132,000	406,408,000
Fee income from revenue sharing agreement	102,758,000				120,927,000			353,740,000	345,520,000
Accrued investment income	117,166,000			102,724,000				117,166,000		102,724,000
Contributed capital								0		0
Prudential Insurance
Related Party Transaction [Line Items]
Stock option program plan expense	0.0				0.0			100,000	100,000
Deferred compensation program expense	200,000				0.0			500,000	500,000
Pension plan expense	900,000				500,000			2,000,000.0	1,500,000
Welfare plan expense	600,000				500,000			$ 1,600,000	1,500,000
Defined contribution plan employer matching contribution percent								4.00%
Defined contribution plan, cost recognized	300,000				200,000			$ 800,000	700,000
Affiliated Entity
Related Party Transaction [Line Items]
Net investment income	900,000							1,200,000
Accrued interest receivable related to long-term notes receivables	200,000			0.0				200,000		0.0
Revenue related to long-term notes receivable	(300,000)				(100,000)			(1,100,000)	100,000
Accrued investment income	200,000							200,000
Interest expense related to loans payable	9,000,000				38,000,000			45,000,000	78,000,000
Affiliated Entity | PAD
Related Party Transaction [Line Items]
Commissions and fees	61,000,000				24,000,000			113,000,000	74,000,000
Affiliated Entity | ASTISI and PGIM Investments
Related Party Transaction [Line Items]
Fee income from revenue sharing agreement	23,000,000				24,000,000			66,000,000	72,000,000
Affiliated Entity | PGIM
Related Party Transaction [Line Items]
Investment expense	6,000,000				4,000,000			16,000,000	12,000,000
Prudential Financial Joint Venture
Related Party Transaction [Line Items]
Other invested assets	514,000,000			391,000,000				514,000,000		$ 391,000,000
Net investment income	8,000,000				3,000,000			5,000,000	11,000,000
Prudential Financial
Related Party Transaction [Line Items]
Company's share of corporate expenses (benefits)	5,000,000				4,000,000			11,000,000	$ 12,000,000
Line of credit facility, maximum borrowing capacity	9,000,000,000							$ 9,000,000,000
PAI
Related Party Transaction [Line Items]
Return of capital	$ 192,000,000	$ 173,000,000	$ 207,000,000	$ 241,000,000	$ 245,000,000	$ 247,000,000	$ 245,000,000