Investments (Rollforward of the Allowance for Credit Losses for Mortgage Loans by Portfolio Segment) (Details) - Mortgage Loans $ in Millions	6 Months Ended
	Jun. 30, 2020 USD ($)
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, allowance for credit losses, beginning of period	$ 64
Current period provision	26
Financing receivable, allowance for credit losses, end of period	92
Cumulative Effect, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, allowance for credit losses, beginning of period	2
Cumulative Effect, Adjusted Balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, allowance for credit losses, beginning of period	66
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, allowance for credit losses, beginning of period	47
Current period provision	10
Financing receivable, allowance for credit losses, end of period	37
Commercial | Cumulative Effect, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, allowance for credit losses, beginning of period	(20)
Commercial | Cumulative Effect, Adjusted Balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, allowance for credit losses, beginning of period	27
Agricultural
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, allowance for credit losses, beginning of period	10
Current period provision	(1)
Financing receivable, allowance for credit losses, end of period	16
Agricultural | Cumulative Effect, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, allowance for credit losses, beginning of period	7
Agricultural | Cumulative Effect, Adjusted Balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, allowance for credit losses, beginning of period	17
Residential
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, allowance for credit losses, beginning of period	7
Current period provision	17
Financing receivable, allowance for credit losses, end of period	39
Residential | Cumulative Effect, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, allowance for credit losses, beginning of period	15
Residential | Cumulative Effect, Adjusted Balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, allowance for credit losses, beginning of period	$ 22