Debt Instrument, Additional Repurchased Face Amount

No definition available.

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- Definition

Debt Instrument, Convertible, Maximum Percentage Of Product Of Last Reported Sale Price And Conversion Rate

+ References

No definition available.

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- Definition

Long-Term And Short-Term Debt, Gross

+ References

No definition available.

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- Definition

Schedule of Borrowings [Line Items]

+ References

No definition available.

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- Definition

Threshold period of specified consecutive trading days within which common stock price to conversion price of convertible debt instrument must exceed threshold percentage for specified number of trading days to trigger conversion feature.

+ References

No definition available.

+ Details

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- Definition

Minimum percentage of common stock price to conversion price of convertible debt instruments to determine eligibility of conversion.

+ References

No definition available.

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- Definition

Threshold number of specified trading days that common stock price to conversion price of convertible debt instruments must exceed threshold percentage within a specified consecutive trading period to trigger conversion feature.

+ References

No definition available.

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- Definition

Face (par) amount of debt instrument at time of issuance.

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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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- Definition

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

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- Definition

Face (par) amount of the original debt instrument that was repurchased.

+ References

No definition available.

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- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

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- Definition

Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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- Definition

Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, excluding amortization of debt discount (premium) and financing costs.

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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- Definition

The cash inflow from the issuance of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder.

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- Definition

Fair value of the securities pledged as collateral against securities loaned.

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Borrowings - Narrative (Details)	1 Months Ended		3 Months Ended				6 Months Ended
Borrowings - Narrative (Details)	Aug. 31, 2025 USD ($)	Aug. 31, 2021 USD ($)	Jun. 30, 2026 USD ($)	Sep. 30, 2025 USD ($)	Jun. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Jun. 30, 2026 USD ($) day	Jun. 30, 2025 USD ($)	Jun. 05, 2026 USD ($)	Jun. 04, 2026 USD ($)	Apr. 22, 2026 USD ($)	Apr. 21, 2026 USD ($)	Dec. 31, 2025 USD ($)	Nov. 30, 2024 USD ($)
Schedule of Borrowings [Line Items]
Total payments due			$ 2,031,583,000				$ 2,031,583,000						$ 1,860,774,000
Convertible senior notes
Schedule of Borrowings [Line Items]
Total payments due			1,687,794,000				$ 1,687,794,000						1,687,794,000
Conversion price maximum threshold							130.00%
Trading days \| day							20
Consecutive trading days \| day							30
Redemption price (in percent)		100.00%					100.00%
Interest expense			0		$ 0		$ 6,900,000	$ 7,200,000
Convertible senior notes \| Conversion Period One
Schedule of Borrowings [Line Items]
Conversion price maximum threshold							130.00%
Trading days \| day							20
Consecutive trading days \| day							30
Convertible senior notes \| Conversion Period Two
Schedule of Borrowings [Line Items]
Trading days \| day							5
Consecutive trading days \| day							5
Percentage of the last reported sale price							98.00%
Risk retention financing facility \| Secured debt
Schedule of Borrowings [Line Items]
Total payments due			92,031,000				$ 92,031,000						75,647,000
Aggregate principal amount					$ 100,000,000.0			$ 100,000,000.0			$ 200,000,000.0	$ 100,000,000.0
Securities loaned, fair value of collateral			$ 91,300,000				$ 91,300,000
Weighted average interest rate			0.40%				0.40%
Risk retention financing facility \| Secured debt \| Variable Interest Entity, Primary Beneficiary \| Consolidated securitization
Schedule of Borrowings [Line Items]
Securities loaned, fair value of collateral			$ 1,700,000				$ 1,700,000
Risk retention financing facility \| Secured debt \| Location, Statement of Financial Position, Balance [Axis]: us-gaap:NotesReceivableFairValueDisclosure
Schedule of Borrowings [Line Items]
Securities loaned, fair value of collateral			89,700,000				89,700,000
2026 Notes \| Convertible senior notes
Schedule of Borrowings [Line Items]
Aggregate principal amount		$ 661,300,000
Stated interest rate		0.25%
Repurchase amount	$ 232,600,000					$ 334,200,000
Additional repurchased amount						27,900,000
Gain (loss) on extinguishment of debt				$ 7,200,000		33,400,000
Gross debt issuance cost		$ 15,700,000
Effective interest rate		0.70%
2029 Notes \| Convertible senior notes
Schedule of Borrowings [Line Items]
Aggregate principal amount						$ 431,300,000
Stated interest rate						2.00%
Proceeds from convertible notes issuance, net of debt issuance costs paid to lender						$ 302,400,000
Gross debt issuance cost						$ 10,400,000
Effective interest rate						2.50%
2030 Notes \| Convertible senior notes
Schedule of Borrowings [Line Items]
Aggregate principal amount														$ 500,000,000.0
Stated interest rate														1.00%
Gross debt issuance cost														$ 11,800,000
Effective interest rate														1.40%
2032 Notes \| Convertible senior notes
Schedule of Borrowings [Line Items]
Aggregate principal amount	$ 690,000,000.0
Stated interest rate	0.00%
Proceeds from convertible notes issuance, net of debt issuance costs paid to lender	$ 224,200,000
Gross debt issuance cost	$ 14,400,000
Effective interest rate	0.30%
Revolving Credit Facility \| Upstart Loan Trust
Schedule of Borrowings [Line Items]
Maximum borrowing capacity			400,000,000				400,000,000		$ 400,000,000.0	$ 325,000,000.0
Total payments due			$ 177,451,000				$ 177,451,000		$ 175,000,000.0				$ 23,025,000