Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) segment	Sep. 30, 2017 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment			3
Revenues
Premium income	$ 130,953	$ 145,504	$ 353,790	$ 365,408
Fee income	290,790	264,304	853,450	786,758
Other revenue	3,078	3,322	9,140	9,367
Net investment income	322,425	300,582	988,037	911,274
Investment gains (losses), net	4,409	13,861	922	24,171
Total revenues	751,655	727,573	2,205,339	2,096,978
Benefits and expenses:
Policyholder benefits	342,994	344,241	942,264	953,213
Operating expenses	319,992	315,063	986,316	947,555
Total benefits and expenses	662,986	659,304	1,928,580	1,900,768
Income before income taxes	88,669	68,269	276,759	196,210
Income tax expense	17,287	21,688	58,091	64,973
Net income	71,382	46,581	218,668	131,237
Individual Markets
Revenues
Premium income	123,915	125,757	297,456	302,017
Fee income	31,984	27,780	96,778	82,960
Other revenue	0	0	0	0
Net investment income	191,167	185,447	585,900	562,440
Investment gains (losses), net	6,020	2,389	21,467	7,010
Total revenues	353,086	341,373	1,001,601	954,427
Benefits and expenses:
Policyholder benefits	284,538	272,396	758,101	740,655
Operating expenses	43,222	41,332	144,247	127,137
Total benefits and expenses	327,760	313,728	902,348	867,792
Income before income taxes	25,326	27,645	99,253	86,635
Income tax expense	3,640	9,398	17,672	29,579
Net income	21,686	18,247	81,581	57,056
Empower Retirement
Revenues
Premium income	914	764	2,589	1,908
Fee income	257,038	234,957	751,341	698,850
Other revenue	3,078	3,322	9,140	9,367
Net investment income	118,960	103,334	365,257	313,710
Investment gains (losses), net	(1,612)	11,472	(20,596)	17,168
Total revenues	378,378	353,849	1,107,731	1,041,003
Benefits and expenses:
Policyholder benefits	54,652	53,736	159,899	152,067
Operating expenses	269,131	255,623	787,883	760,564
Total benefits and expenses	323,783	309,359	947,782	912,631
Income before income taxes	54,595	44,490	159,949	128,372
Income tax expense	11,761	13,641	36,538	42,063
Net income	42,834	30,849	123,411	86,309
Other
Revenues
Premium income	6,124	18,983	53,745	61,483
Fee income	1,768	1,567	5,331	4,948
Other revenue	0	0	0	0
Net investment income	12,298	11,801	36,880	35,124
Investment gains (losses), net	1	0	51	(7)
Total revenues	20,191	32,351	96,007	101,548
Benefits and expenses:
Policyholder benefits	3,804	18,109	24,264	60,491
Operating expenses	7,639	18,108	54,186	59,854
Total benefits and expenses	11,443	36,217	78,450	120,345
Income before income taxes	8,748	(3,866)	17,557	(18,797)
Income tax expense	1,886	(1,351)	3,881	(6,669)
Net income	$ 6,862	$ (2,515)	$ 13,676	$ (12,128)