Investments (Distribution By Contractual Maturity Of Available-For-Sale and Held-To-Maturity Investments) (Detail) - Fixed Maturities [Member] $ in Millions	Sep. 30, 2020 USD ($)
Available For Sale Securities [Abstract]
Due in one year or less	$ 560
Due after one year through five years	473
Due after five years through ten years	269
Due after ten years	657
Mortgage-Backed and Asset-Backed	552
Total Available-For-Sale, amortized cost	2,511
Due in one year or less	562
Due after one year through five years	490
Due after five years through ten years	297
Due after ten years	791
Mortgage-Backed and Asset-Backed	561
Total Available-For-Sale, fair value	2,701
Variable Interest Entity Primary Beneficiary [Member]
Held To Maturity Securities [Abstract]
Due in one year or less	0
Due after one year through five years	0
Due after five years through ten years	0
Due after ten years	575
Mortgage-Backed and Asset-Backed	0
Total held-to-maturity, amortized cost	575
Due in one year or less	0
Due after one year through five years	0
Due after five years through ten years	0
Due after ten years	575
Mortgage-Backed and Asset-Backed	0
Held-To-Maturity Securities Fair Value	$ 575