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Investments - Gross unrealized losses and fair value by the type and length of time held in continuous unrealized loss position (Details) $ in Millions | Sep. 30, 2020 USD ($) contract | Dec. 31, 2019 USD ($) contract
--- | --- | ---
Total unrealized losses |  |
Total unrealized losses | $ (1) |
U.S. government and agencies |  |
Less than 12 months |  |
Number of issues | contract | 17 | 31
Fair value | $ 350 | $ 1,713
Unrealized losses | $ (1) | $ (26)
12 months or more |  |
Number of issues | contract | 0 | 10
Fair value | $ 0 | $ 26
Unrealized losses | $ 0 | 0
Total unrealized losses |  |
Total unrealized losses |  | $ (26)
Municipal |  |
Less than 12 months |  |
Number of issues | contract | 246 | 307
Fair value | $ 511 | $ 576
Unrealized losses | $ (8) | $ (9)
12 months or more |  |
Number of issues | contract | 0 | 1
Fair value | $ 0 | $ 14
Unrealized losses | 0 | (2)
Total unrealized losses |  |
Total unrealized losses | $ (8) | $ (11)
Corporate |  |
Less than 12 months |  |
Number of issues | contract | 428 | 186
Fair value | $ 3,969 | $ 1,392
Unrealized losses | $ (155) | $ (20)
12 months or more |  |
Number of issues | contract | 33 | 65
Fair value | $ 200 | $ 485
Unrealized losses | (39) | (27)
Total unrealized losses |  |
Total unrealized losses | $ (194) | $ (47)
Foreign government |  |
Less than 12 months |  |
Number of issues | contract | 7 | 55
Fair value | $ 14 | $ 412
Unrealized losses | $ 0 | $ (4)
12 months or more |  |
Number of issues | contract | 0 | 6
Fair value | $ 0 | $ 102
Unrealized losses | 0 | (1)
Total unrealized losses |  |
Total unrealized losses | $ 0 | $ (5)
ABS |  |
Less than 12 months |  |
Number of issues | contract | 36 | 36
Fair value | $ 392 | $ 193
Unrealized losses | $ (7) | $ (2)
12 months or more |  |
Number of issues | contract | 17 | 23
Fair value | $ 67 | $ 160
Unrealized losses | (7) | (4)
Total unrealized losses |  |
Total unrealized losses | $ (14) | $ (6)
MBS |  |
Less than 12 months |  |
Number of issues | contract | 12 | 27
Fair value | $ 1 | $ 15
Unrealized losses | $ 0 | $ 0
12 months or more |  |
Number of issues | contract | 80 | 123
Fair value | $ 0 | $ 14
Unrealized losses | 0 | (1)
Total unrealized losses |  |
Total unrealized losses | $ 0 | $ (1)
Fixed income securities |  |
Less than 12 months |  |
Number of issues | contract | 746 | 642
Fair value | $ 5,237 | $ 4,301
Unrealized losses | $ (171) | $ (61)
12 months or more |  |
Number of issues | contract | 130 | 228
Fair value | $ 267 | $ 801
Unrealized losses | (46) | (35)
Total unrealized losses |  |
Total unrealized losses | $ (217) | $ (96)
Investment grade fixed income securities |  |
Less than 12 months |  |
Number of issues | contract | 508 | 581
Fair value | $ 3,485 | $ 3,878
Unrealized losses | $ (63) | $ (41)
12 months or more |  |
Number of issues | contract | 99 | 185
Fair value | $ 119 | $ 594
Unrealized losses | (20) | (20)
Total unrealized losses |  |
Total unrealized losses | $ (83) | $ (61)
Below investment grade fixed income securities |  |
Less than 12 months |  |
Number of issues | contract | 238 | 61
Fair value | $ 1,752 | $ 423
Unrealized losses | $ (108) | $ (20)
12 months or more |  |
Number of issues | contract | 31 | 43
Fair value | $ 148 | $ 207
Unrealized losses | (26) | (15)
Total unrealized losses |  |
Total unrealized losses | $ (134) | $ (35)

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