Employee Benefit Arrangements - Obligations in Excess of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,964
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	2,410	$ 2,140	$ 2,294
Accumulated benefit obligation	2,404	2,134
Fair value of plan assets	1,960	1,605	$ 1,764
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 18	$ 16