Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Administration, recordkeeping and servicing fees	$ 168,510		$ 327,501
Investment advisory and asset management fees	73,807		147,231
Other fee income	44,379		87,928
Total Fee Income	286,696	$ 267,338	562,660	$ 522,453
Customer contract receivables	246,719		246,719		$ 234,256
Deferred contract costs	44,528		44,528
Individual Markets
Disaggregation of Revenue [Line Items]
Administration, recordkeeping and servicing fees	1,162		2,302
Investment advisory and asset management fees	3,443		6,698
Other fee income	28,562		55,795
Total Fee Income	33,167	29,199	64,795	55,180
Empower Retirement
Disaggregation of Revenue [Line Items]
Administration, recordkeeping and servicing fees	167,348		325,199
Investment advisory and asset management fees	68,680		136,970
Other fee income	15,817		32,133
Total Fee Income	251,845	236,573	494,302	463,892
Other
Disaggregation of Revenue [Line Items]
Administration, recordkeeping and servicing fees	0		0
Investment advisory and asset management fees	1,684		3,563
Other fee income	0		0
Total Fee Income	$ 1,684	$ 1,566	$ 3,563	$ 3,381