Investments (Credit Quality of Commercial 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
Commercial Mortgage Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	3,110
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	6,410
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	8,652
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	7,905
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	6,187
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	17,358
Financing Receivable, Revolving	1,980
Mortgage Loans, Gross	$ 51,602	$ 52,434
Loans Receivable Commercial Mortgage Percentage	100.00%
Commercial Mortgage Loans | Greater than 1.20x
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 2,937
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	5,671
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	8,214
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	7,880
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	5,667
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	15,787
Financing Receivable, Revolving	1,980
Mortgage Loans, Gross	$ 48,136
Loans Receivable Commercial Mortgage Percentage	93.30%
Commercial Mortgage Loans | 1.00x - 1.20x
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 86
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	450
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	65
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	25
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	135
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	787
Financing Receivable, Revolving	0
Mortgage Loans, Gross	$ 1,548
Loans Receivable Commercial Mortgage Percentage	3.00%
Commercial Mortgage Loans | Less than 1.00x
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 87
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	289
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	373
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	385
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	784
Financing Receivable, Revolving	0
Mortgage Loans, Gross	$ 1,918
Loans Receivable Commercial Mortgage Percentage	3.70%
Commercial Mortgage Loans | Less than 65%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 2,289
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	5,108
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	4,305
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	5,301
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	4,069
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	12,943
Financing Receivable, Revolving	1,980
Mortgage Loans, Gross	$ 35,995
Loans Receivable Commercial Mortgage Percentage	69.80%
Commercial Mortgage Loans | 65% to 75%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 747
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,262
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	4,003
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	2,458
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,465
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2,673
Financing Receivable, Revolving	0
Mortgage Loans, Gross	$ 12,608
Loans Receivable Commercial Mortgage Percentage	24.40%
Commercial Mortgage Loans | 76% to 80%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 66
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	40
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	340
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	66
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	404
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	503
Financing Receivable, Revolving	0
Mortgage Loans, Gross	$ 1,419
Loans Receivable Commercial Mortgage Percentage	2.70%
Commercial Mortgage Loans | Greater than 80%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 8
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	4
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	80
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	249
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,239
Financing Receivable, Revolving	0
Mortgage Loans, Gross	$ 1,580
Loans Receivable Commercial Mortgage Percentage	3.10%