Cash deposited in a special reserve account for the exclusive benefit of customers pursuant to SEC Regulations.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=116631393&loc=SL116631396-227033

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Certificate of deposits fixed interest rates range

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Maximum Money Market And Demand Deposit Accounts Purchasable

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Deposits - Narrative (Details) - USD ($)		3 Months Ended
Deposits - Narrative (Details) - USD ($)	Apr. 09, 2020	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Required reserve based on the outstanding customer deposits			$ 24,900,000
Maximum money market and demand deposit accounts purchasable		$ 125,000,000.0
Outstanding balance of ICS purchases		$ 0	$ 0
Minimum
Debt Instrument [Line Items]
Certificate of deposits, fixed interest rates range (as a percent)		1.45%	1.80%
Maximum
Debt Instrument [Line Items]
Certificate of deposits, fixed interest rates range (as a percent)		3.52%	3.52%
Subsequent Event
Debt Instrument [Line Items]
Proceeds from issuing certificates of deposit	$ 315,000,000.0
Subsequent Event \| Minimum
Debt Instrument [Line Items]
Certificate of deposits, fixed interest rates range (as a percent)	1.25%
Subsequent Event \| Maximum
Debt Instrument [Line Items]
Certificate of deposits, fixed interest rates range (as a percent)	1.40%