Stockholders' Deficit- Additional Information (Detail) - USD ($)	9 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Common stock, shares authorized	22,701,005,000	4,000,000,000
Preferred stock, shares authorized	2,000,000,000	0
minimum ownership threshold	$ 100,000,000
Number of treasury stock	0	6,392,571
Dividends declared	$ 0
Common Class A [Member]
Common stock, shares authorized	20,000,000,000	2,200,000,000
Number of shares sold in the transaction	206,500,523
Sale price per share	$ 4.65
Proceeds from sale of equity	$ 942,500,000
Payment of stock issuance cost	$ 17,700,000
Common Class A [Member] \| SOMPO [Member]
Number of shares sold in the transaction	107,526,881
Common Class B [Member]
Common stock, shares authorized	2,700,000,000	1,800,000,000
Number of shares issued for conversion	335,000
Number of shares exchanged	1,005,000
Common Class B [Member] \| Redeemable Convertible Preferred Stock [Member]
Convertible Preferred Stock, Shares Issued upon Conversion	4,017,378
Common Class B [Member] \| Convertible preferred stock [Member]
Convertible Preferred Stock, Shares Issued upon Conversion	793,725,807
Common Class F [Member]
Common stock, shares authorized	1,005,000	0
voting power	50.00%

Number Of Shares Exchanged.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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The number of shares converted in a noncash (or part noncash) transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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Number of shares issued for each share of convertible preferred stock that is converted.

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Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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