Investments (Credit Quality of Agricultural and Residential Mortgage Loans) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage Loans, Gross	$ 81,927	$ 84,344
Mortgage Loans in Process of Foreclosure, Amount	83	103
Agricultural Mortgage Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	1,228
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	3,484
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	2,260
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	2,934
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,025
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	6,153
Financing Receivable, Revolving	960
Mortgage Loans, Gross	$ 18,044	18,128
Loans Receivable Agricultural Mortgage Percentage	100.00%
Agricultural Mortgage Loans | Less than 65%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 994
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	3,079
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,951
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	2,833
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	973
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	5,518
Financing Receivable, Revolving	860
Mortgage Loans, Gross	$ 16,208
Loans Receivable Agricultural Mortgage Percentage	89.80%
Agricultural Mortgage Loans | 65% to 75%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 234
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	405
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	175
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	101
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	52
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	582
Financing Receivable, Revolving	100
Mortgage Loans, Gross	$ 1,649
Loans Receivable Agricultural Mortgage Percentage	9.10%
Agricultural Mortgage Loans | 76% to 80%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	11
Financing Receivable, Revolving	0
Mortgage Loans, Gross	$ 11
Loans Receivable Agricultural Mortgage Percentage	0.10%
Agricultural Mortgage Loans | Greater than 80%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	134
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	42
Financing Receivable, Revolving	0
Mortgage Loans, Gross	$ 176
Loans Receivable Agricultural Mortgage Percentage	1.00%
Residential Mortgage Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 103
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	530
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,839
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	857
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	384
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	8,568
Financing Receivable, Revolving	0
Mortgage Loans, Gross	$ 12,281	$ 13,782
Loans Receivable Residential Mortgage Percentage	100.00%
Residential Mortgage Loans | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 103
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	526
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,783
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	840
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	378
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	8,177
Financing Receivable, Revolving	0
Mortgage Loans, Gross	$ 11,807
Loans Receivable Residential Mortgage Percentage	96.10%
Residential Mortgage Loans | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	56
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	17
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	6
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	391
Financing Receivable, Revolving	0
Mortgage Loans, Gross	$ 474
Loans Receivable Residential Mortgage Percentage	3.90%