Control of total voting power.

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Minimum ownership threshold.

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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 cash inflow from the issuance of common stock, preferred stock, treasury stock, stock options, and other types of equity.

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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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Stockholders' Deficit- Additional Information (Detail) - USD ($)		9 Months Ended	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Common stock, shares authorized			22,701,005,000	4,000,000,000
Preferred stock, shares authorized	2,000,000,000	2,000,000,000	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	20,000,000,000	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	2,700,000,000	2,700,000,000	1,800,000,000
Number of shares issued for conversion		335,000
Common Class B [Member] \| Redeemable Convertible Preferred Stock [Member] \| Direct Listing [Member]
Number of shares issued for conversion	4,017,378
Common Class B [Member] \| Convertible preferred stock [Member] \| Direct Listing [Member]
Number of shares issued for conversion	793,725,807
Common Class F [Member]
Common stock, shares authorized	1,005,000	1,005,000	1,005,000	0
Voting power			50.00%
Undesignated Preferred Stock [Member] \| Direct Listing [Member]
Preferred stock, shares authorized	2,000,000,000	2,000,000,000