Deposits (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Deposit Liability [Line Items]
Customer deposits	$ 334,900	$ 245,600
Contractual deposits with maturities within 1 year	402,900	250,000
Interest-bearing money market deposits	684,800	727,500
HSA deposits	4,758,000	4,200,000
Short-term deposits	$ 6,180,500	$ 5,423,100
Weighted average cost of funds on contractual deposits outstanding (as a percent)	4.02%	4.00%
Weighted average cost of interest-bearing money market deposits outstanding (as a percent)	4.03%	3.79%
Weighted average cost of HSA deposits outstanding (as a percent)	0.11%	0.11%
Maximum
Deposit Liability [Line Items]
Certificates of deposit, denominations	$ 250	$ 250

The current portion, due within one year or one operating cycle, if longer, of deposits held other than customer deposits.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(20))
-Publisher FASB
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Amount of interest-bearing domestic money market demand account deposit liabilities.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S45
-Paragraph 1
-Publisher FASB
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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The aggregate amount of all domestic and foreign noninterest-bearing deposits liabilities held by the entity.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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The weighted average interest rate for domestic certificates of deposit liabilities.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
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The weighted average interest rate for domestic money market demand account deposit liabilities.

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Certificate of Deposits Maturities, Year One

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Deposits, HSA

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Weighted Average Rate HSA Deposit

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