Segment Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) segment	Jun. 30, 2015 USD ($)
Financial information of the segments
Number of reportable segments | segment			3
Revenues
Premium income	$ 76,818	$ 74,717	$ 231,745	$ 220,420
Fee income	238,364	237,501	463,429	462,778
Other revenue	3,370	1,820	6,519	3,640
Net investment income	355,755	220,169	687,540	579,025
Realized investment gains (losses), net	42,013	15,859	73,283	34,059
Total revenues	716,320	550,066	1,462,516	1,299,922
Benefits and expenses:
Policyholder benefits	263,271	272,319	600,015	599,990
Operating expenses	339,540	288,441	626,332	560,116
Total benefits and expenses	602,811	560,760	1,226,347	1,160,106
Income (loss) before income taxes	113,509	(10,694)	236,169	139,816
Income tax expense (benefit)	39,710	(3,679)	63,748	48,218
Net income (loss)	73,799	(7,015)	172,421	91,598
Operating Segments | Individual Markets
Revenues
Premium income	51,053	51,253	184,339	176,215
Fee income	25,546	24,967	48,269	46,469
Other revenue	0	0	0	0
Net investment income	226,193	155,658	433,886	373,311
Realized investment gains (losses), net	14,771	3,552	26,577	11,952
Total revenues	317,563	235,430	693,071	607,947
Benefits and expenses:
Policyholder benefits	201,472	198,590	468,969	454,914
Operating expenses	54,010	31,424	91,231	67,363
Total benefits and expenses	255,482	230,014	560,200	522,277
Income (loss) before income taxes	62,081	5,416	132,871	85,670
Income tax expense (benefit)	21,247	1,501	45,081	29,724
Net income (loss)	40,834	3,915	87,790	55,946
Operating Segments | Empower Retirement
Revenues
Premium income	362	16	707	16
Fee income	211,414	211,532	412,336	414,353
Other revenue	3,370	1,820	6,519	3,640
Net investment income	117,055	51,079	227,589	178,809
Realized investment gains (losses), net	27,242	12,211	46,713	22,011
Total revenues	359,443	276,658	693,864	618,829
Benefits and expenses:
Policyholder benefits	51,939	47,748	101,856	96,792
Operating expenses	266,857	240,176	498,500	461,206
Total benefits and expenses	318,796	287,924	600,356	557,998
Income (loss) before income taxes	40,647	(11,266)	93,508	60,831
Income tax expense (benefit)	14,486	(3,614)	15,137	20,766
Net income (loss)	26,161	(7,652)	78,371	40,065
Operating Segments | Other
Revenues
Premium income	25,403	23,448	46,699	44,189
Fee income	1,404	1,002	2,824	1,956
Other revenue	0	0	0	0
Net investment income	12,507	13,432	26,065	26,905
Realized investment gains (losses), net	0	96	(7)	96
Total revenues	39,314	37,978	75,581	73,146
Benefits and expenses:
Policyholder benefits	9,860	25,981	29,190	48,284
Operating expenses	18,673	16,841	36,601	31,547
Total benefits and expenses	28,533	42,822	65,791	79,831
Income (loss) before income taxes	10,781	(4,844)	9,790	(6,685)
Income tax expense (benefit)	3,977	(1,566)	3,530	(2,272)
Net income (loss)	$ 6,804	$ (3,278)	$ 6,260	$ (4,413)