Revenues From Contracts With Clients Client Account Fees (Policies)	3 Months Ended
	Dec. 31, 2018
Client Account Fees [Abstract]
Revenue, Performance Obligation, Description of Good or Service	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-bottom:8px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Sweep Program Fees</font></div><div style="line-height:120%;padding-bottom:8px;padding-top:8px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">The Company earns fees generated in lieu of interest income from a multi-bank sweep program with unaffiliated banks and money market funds. Pursuant to contractual arrangements with clients and their introducing-brokers, available cash balances in client accounts are swept into either Federal Deposit Insurance Corporation (“FDIC”) insured cash accounts at unaffiliated banks or unaffiliated money market funds for which the Company earns a portion of the interest income generated by the client balances for administration and recordkeeping. The fees generated by the Company’s multi-bank sweep program are reported net of the balances remitted to the introducing-brokers and the clients of introducing-brokers. These fees are paid and recognized over time to match the continued delivery of the administration and recordkeeping performance obligations to the life of the contract. The fees earned under this program are generally based upon the type of sweep account, prevailing interest rates, and the amount of client balances invested. </font></div></div><div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-bottom:8px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Trade Conversion Revenue </font></div><div style="line-height:120%;padding-bottom:8px;padding-top:8px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Trade conversion revenue includes fees earned from converting foreign ordinary equities into an American Depository Receipt (“ADR”) or Global Depository Receipt (“GDR”) and fees earned from converting an ADR or GDR into foreign ordinary equities on behalf of clients. Trade conversion revenue is reported on a trade date basis. </font></div></div><div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-bottom:8px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Asset Management Fees </font></div><div style="line-height:120%;padding-bottom:8px;padding-top:8px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">The Company earns asset management fees on Company sponsored and managed mutual funds and on the advisory accounts of independent registered investment advisors on the Company’s platform. The Company provides ongoing investment advice and acts as a custodian, providing brokerage and execution services on transactions, and performs administrative services for these accounts. This series of performance obligations transfers control of the services to the client over time as the services are performed. This revenue is recognized ratably over time to match the continued delivery of the performance obligations to the client over the life of the contract. The asset management revenue generated is based on a percentage of the market value of the eligible assets in the clients’ accounts. As such, the consideration for this revenue is variable and this variable consideration is constrained until the market value of eligible assets in the clients’ accounts is determinable.</font></div></div><div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-bottom:8px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Advisory and Consulting Fees</font></div><div style="line-height:120%;padding-bottom:8px;padding-top:8px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Advisory and consulting fees are primarily related to risk management consulting fees which are billed and recognized as revenue on a monthly basis when risk management services are provided. Such agreements are generally for one year periods, but are generally cancelable by either party upon providing thirty days’ written notice to the other party and the amounts are not variable based on client trading activities. This revenue is generally recognized ratably over time to match the continued delivery of the performance obligation to the client over the life of the contract. </font></div></div><div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-bottom:8px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Client Accounts Fees</font></div><div style="line-height:120%;padding-bottom:8px;padding-top:8px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Client accounts fees represent fees earned for custodial, recordkeeping, and administrative functions performed for the securities clearing accounts of clients. These include statement delivery fees, account transfer fees, safekeeping fees, errors and omission insurance fees, platform fees, and other fees. Client account fees that are transactional based, such as account transfer fees, are recognized at a point in time when the related performance obligation is satisfied. Client account fees that are related to ongoing services, such as statement delivery fees and errors and omission insurance fees, are recognized over time. Client account fees that relate to ongoing services are typically billed to clients’ accounts on a monthly or quarterly basis. </font></div></div>