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v3.20.1

Cash and Cash Equivalents - Annual Yield Rates of Bank Deposits, Commercial Paper, Negotiable Certificates of Deposit and Time Deposits and Repurchase Agreements Collateralized by Bonds (Detail) | Dec. 31, 2019 | Dec. 31, 2018
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Bank deposits [Member] | Bottom of range [Member] |  |
Disclosure of cash and cash equivalents [Line Items] |  |
Yield rate | 0.00% | 0.00%
Bank deposits [Member] | Top of Range [Member] |  |
Disclosure of cash and cash equivalents [Line Items] |  |
Yield rate | 0.74% | 0.50%
Commercial paper [Member] | Bottom of range [Member] |  |
Disclosure of cash and cash equivalents [Line Items] |  |
Yield rate | 0.47% | 0.47%
Commercial paper [Member] | Top of Range [Member] |  |
Disclosure of cash and cash equivalents [Line Items] |  |
Yield rate | 0.54% | 0.57%
Negotiable certificate of deposit [Member] | Bottom of range [Member] |  |
Disclosure of cash and cash equivalents [Line Items] |  |
Yield rate | 0.58% | 0.55%
Negotiable certificate of deposit [Member] | Top of Range [Member] |  |
Disclosure of cash and cash equivalents [Line Items] |  |
Yield rate | 0.60% | 0.60%
Time deposits [Member] | Bottom of range [Member] |  |
Disclosure of cash and cash equivalents [Line Items] |  |
Yield rate | 0.09% | 0.09%
Time deposits [Member] | Top of Range [Member] |  |
Disclosure of cash and cash equivalents [Line Items] |  |
Yield rate | 4.40% | 4.40%
Repurchase agreements collateralized by bonds [Member] |  |
Disclosure of cash and cash equivalents [Line Items] |  |
Yield rate | 1.90% |

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