Related Party Transactions (Narrative) (Details) - USD ($)	3 Months Ended					12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2018
Related Party Transaction [Line Items]
Investment expense	$ 3,953,000				$ 3,794,000
Commissions and fees	507,934,000				555,290,000
Other invested assets	334,737,000	$ 348,541,000				$ 348,541,000
Net investment income	125,069,000				96,711,000
Fee income from revenue sharing agreement	109,388,000				99,537,000
Contributed capital	0					0
Prudential Insurance
Related Party Transaction [Line Items]
Stock option program plan expense	0.0				0
Deferred compensation program expense	300,000				200,000
Pension plan expense	500,000				0
Welfare plan expense	$ 500,000				500,000
Defined contribution plan employer matching contribution percent	4.00%
Defined contribution plan, cost recognized	$ 200,000				200,000
Affiliated Entity
Related Party Transaction [Line Items]
Accrued interest receivable related to long-term notes receivables	100,000	300,000				300,000
Revenue related to long-term notes receivable	200,000				100,000
Interest expense related to loans payable	16,000,000				16,000,000
Affiliated Entity | PAD
Related Party Transaction [Line Items]
Commissions and fees	24,000,000				29,000,000
Affiliated Entity | ASTISI and PGIM Investments
Related Party Transaction [Line Items]
Fee income from revenue sharing agreement	24,000,000				27,000,000
Affiliated Entity | PGIM
Related Party Transaction [Line Items]
Investment expense	3,000,000				0
Prudential Financial Joint Venture
Related Party Transaction [Line Items]
Other invested assets	256,000,000	228,000,000				$ 228,000,000
Net investment income	5,000,000				400,000
Prudential Financial
Related Party Transaction [Line Items]
Company's share of corporate expenses (benefits)	4,000,000				4,000,000
Line of credit facility, maximum borrowing capacity	9,000,000,000
PAI
Related Party Transaction [Line Items]
Return of capital	$ 245,000,000	$ 225,000,000	$ 250,000,000	$ 250,000,000	$ 300,000,000