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Investments (Distribution Of Securities By Percentage Of Fair Value Below Book Value By More Than 5% For A Continuous Twelve Month Period Or Longer) (Detail) - Unrealized loss position > 12 months [Member] $ in Millions | Jun. 30, 2023 USD ($) security
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> 5% To 15% [Member] |
Available For Sale Securities [Abstract] |
Number of securities | security | 253
Book Value | $ 474
Fair Value | $ 426
Held To Maturity Securities [Abstract] |
Percentage Of Fair Value Below Book Value Minimum | 5.00%
Percentage Of Fair Value Below Book Value Maximum | 15.00%
> 15% To 25% [Member] |
Available For Sale Securities [Abstract] |
Number of securities | security | 191
Book Value | $ 430
Fair Value | $ 347
Held To Maturity Securities [Abstract] |
Percentage Of Fair Value Below Book Value Minimum | 15.00%
Percentage Of Fair Value Below Book Value Maximum | 25.00%
> 25% To 50% [Member] |
Available For Sale Securities [Abstract] |
Number of securities | security | 100
Book Value | $ 184
Fair Value | $ 128
Held To Maturity Securities [Abstract] |
Percentage Of Fair Value Below Book Value Minimum | 25.00%
Percentage Of Fair Value Below Book Value Maximum | 50.00%
> 50% [Member] |
Available For Sale Securities [Abstract] |
Number of securities | security | 2
Book Value | $ 0
Fair Value | $ 0
Held To Maturity Securities [Abstract] |
Percentage Of Fair Value Below Book Value Minimum | 50.00%
Greater Than 5% [Member] |
Available For Sale Securities [Abstract] |
Number of securities | security | 546
Book Value | $ 1,088
Fair Value | $ 901

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