Investments (Past Due and Interest Accrual Status of Mortgage Loans) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Nonaccrual [Line Items]
Mortgage Loans, Gross	$ 81,927	$ 84,344
Greater than 90 Days Past Due and Still Accruing	11	91
Financing Receivable, Nonaccrual	888	1,117
Financial Asset, Past Due
Financing Receivable, Nonaccrual [Line Items]
Mortgage Loans, Gross	701	818
Commercial Mortgage Loans
Financing Receivable, Nonaccrual [Line Items]
Mortgage Loans, Gross	51,602	52,434
Greater than 90 Days Past Due and Still Accruing	0	7
Financing Receivable, Nonaccrual	163	317	$ 176
Commercial Mortgage Loans | Financial Asset, Past Due
Financing Receivable, Nonaccrual [Line Items]
Mortgage Loans, Gross	0	10
Residential Mortgage Loans
Financing Receivable, Nonaccrual [Line Items]
Mortgage Loans, Gross	12,281	13,782
Greater than 90 Days Past Due and Still Accruing	8	64
Financing Receivable, Nonaccrual	466	534	418
Residential Mortgage Loans | Financial Asset, Past Due
Financing Receivable, Nonaccrual [Line Items]
Mortgage Loans, Gross	474	556
Agricultural Mortgage Loans
Financing Receivable, Nonaccrual [Line Items]
Mortgage Loans, Gross	18,044	18,128
Greater than 90 Days Past Due and Still Accruing	3	20
Financing Receivable, Nonaccrual	259	266	$ 137
Agricultural Mortgage Loans | Financial Asset, Past Due
Financing Receivable, Nonaccrual [Line Items]
Mortgage Loans, Gross	$ 227	$ 252