Employee Benefit Arrangements - Net Periodic Benefit Costs and Other Changes in Plan Assets and Future Amortizaion of Prior Service Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Periodic (Benefit) Costs Recognized in Consolidated Statements of Operations:
Net (gain) loss recognition	$ (4)	$ 50	$ 14
Other Changes in Plan Assets and Benefit Obligations Recognized in AOCI:
Amortization of prior service (credit) cost	4	11	15
Total recognized in AOCI	4	11	15
Pension Plan
Net Periodic (Benefit) Costs Recognized in Consolidated Statements of Operations:
Service cost	24	25	24
Interest cost	92	86	93
Expected return on plan assets	(113)	(129)	(115)
Amortization of prior service cost (credit)	0	(9)	(10)
(Gain) loss recognized due to curtailment	1	0	1
Net (gain) loss recognition	(4)	50	14
Net periodic (benefit) costs	0	23	7
Other Changes in Plan Assets and Benefit Obligations Recognized in AOCI:
Amortization of prior service (credit) cost	0	9	10
(Credit) cost recognized due to curtailment	(1)	0	2
Total recognized in AOCI	(1)	9	12
Total recognized in net periodic (benefit) costs and AOCI	(1)	32	19
Other Postretirement Benefits
Net Periodic (Benefit) Costs Recognized in Consolidated Statements of Operations:
Net periodic (benefit) costs	$ (2)	$ (6)	$ (2)