Joint Venture (Detail) - USD ($)		1 Months Ended	3 Months Ended
	May 10, 2023	Feb. 28, 2019	Mar. 31, 2024	Mar. 31, 2023
Schedule of Equity Method Investments [Line Items]
Interest expense			$ 10,363,000	$ 10,012,000
6.0% Notes Due 2026
Schedule of Equity Method Investments [Line Items]
Interest expense			$ 200,000
6.0% Notes Due 2026 | Unsecured Debt
Schedule of Equity Method Investments [Line Items]
Interest rate	6.00%
Songhua River Investment Limited | 6.0% Notes Due 2026
Schedule of Equity Method Investments [Line Items]
Proceeds from debt, net of issuance costs	$ 14,700,000
Roblox China Holding Corp
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percentage		51.00%
Roblox China Holding Corp | 6.0% Notes Due 2026
Schedule of Equity Method Investments [Line Items]
Proceeds from debt, net of issuance costs	15,300,000
Roblox China Holding Corp | 6.0% Notes Due 2026 | Unsecured Debt
Schedule of Equity Method Investments [Line Items]
Debt instrument, aggregated principal amount	$ 30,000,000
Debt instrument, term of maturity date extension	2 years
Roblox China Holding Corp | Songhua River Investment Limited
Schedule of Equity Method Investments [Line Items]
Minority interest percentage in joint venture		49.00%
Roblox China Holding Corp | Songhua River Investment Limited
Schedule of Equity Method Investments [Line Items]
Contribution by non controlling interest to the joint venture		$ 50,000,000