Investments (Credit Quality of Agricultural and Residential Mortgage Loans) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage Loans, Gross	$ 81,393	$ 84,344
Mortgage Loans in Process of Foreclosure, Amount	74	103
Residential Mortgage Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	346
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	514
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,556
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	704
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	323
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	8,261
Financing Receivable, Revolving	0
Mortgage Loans, Gross	$ 11,704	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	$ 344
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	512
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,501
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	689
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	319
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	7,898
Financing Receivable, Revolving	0
Mortgage Loans, Gross	$ 11,263
Loans Receivable Residential Mortgage Percentage	96.20%
Residential Mortgage Loans | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 2
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	2
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	55
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	15
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	4
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	363
Financing Receivable, Revolving	0
Mortgage Loans, Gross	$ 441
Loans Receivable Residential Mortgage Percentage	3.80%
Agricultural Mortgage Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 1,795
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	3,485
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	2,220
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	2,866
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,007
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	5,982
Financing Receivable, Revolving	998
Mortgage Loans, Gross	$ 18,353	$ 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	$ 1,460
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	3,092
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,972
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	2,749
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	967
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	5,345
Financing Receivable, Revolving	890
Mortgage Loans, Gross	$ 16,475
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	$ 335
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	393
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	172
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	117
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	40
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	580
Financing Receivable, Revolving	108
Mortgage Loans, Gross	$ 1,745
Loans Receivable Agricultural Mortgage Percentage	9.50%
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	0.00%
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	76
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	46
Financing Receivable, Revolving	0
Mortgage Loans, Gross	$ 122
Loans Receivable Agricultural Mortgage Percentage	0.70%