Segment Information - Reconciliation of Segment Operating Revenues to Consolidation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Total revenues	$ 2,588	$ 1,473	$ 5,396	$ 4,855
Operating Segments | Retirement Services
Segment Reporting Information [Line Items]
Total revenues	1,776	936	4,901	3,078
Operating Segments | Corporate and Other
Segment Reporting Information [Line Items]
Total revenues	18	94	71	265
Non-operating adjustments
Segment Reporting Information [Line Items]
Change in fair values of derivatives and embedded derivatives – index annuities, net of offsets	884	379	823	1,181
Investment gains (losses), net of offsets	(82)	63	(337)	326
Variable Interest Entity Expense and Noncontrolling Interest	(1)	0	1	0
Other Nonoperating Income	$ (7)	$ 1	$ (63)	$ 5