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Assets and Liabilities, at Fair Value - Financial Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Millions | Jun. 30, 2021 | Sep. 30, 2020 | Jun. 30, 2020
--- | --- | --- | ---
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Assets | $ 1,075.6 | $ 952.6 | $ 465.2
Cash and cash equivalents | 96.1 | 2.6 |
Cash and securities segregated under federal and other regulation | 2,325.5 | 1,920.2 |
Financial instruments owned | 3,467.2 | 2,727.7 |
Physical commodities inventory | 484.8 | 281.1 |
Accounts payable and other accrued liabilities - contingent liabilities | 302.7 | 272.6 |
Payable to broker-dealers, clearing organizations and counterparties | 375.5 | 537.5 |
Financial instruments sold, not yet purchased | 1,764.2 | 686.0 |
Fair Value, Recurring |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Cash and cash equivalents | 20.2 | 16.0 |
Cash and securities segregated under federal and other regulation | 96.1 | 2.6 |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 1,028.8 | 1,775.8 |
Receivables from clients - Derivatives | 5.1 | 1.5 |
Financial instruments owned | 3,467.2 | 2,727.7 |
Total assets at fair value | 4,993.7 | 4,739.3 |
Payables to clients - Derivatives | (495.7) | (222.7) |
Total liabilities at fair value | 1,281.3 | 479.5 |
Fair Value, Recurring | TBA and forward settling securities |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Payable to broker-dealers, clearing organizations and counterparties | 12.4 | 10.2 |
Fair Value, Recurring | Derivatives |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Payable to broker-dealers, clearing organizations and counterparties | 0.0 | 4.5 |
Fair Value, Recurring | Payables to Broker-dealers, Clearing Organizations and Counterparties |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Payable to broker-dealers, clearing organizations and counterparties | 12.4 | 14.7 |
Fair Value, Recurring | Contingent Consideration |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Accounts payable and other accrued liabilities - contingent liabilities | 0.4 | 1.5 |
Fair Value, Recurring | Physical commodities inventory |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Physical commodities inventory | 376.3 | 215.7 |
Fair Value, Recurring | Equity securities |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 502.3 | 264.3 |
Financial instruments sold, not yet purchased | 404.3 | 232.9 |
Fair Value, Recurring | Corporate and municipal bonds |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 150.5 | 66.9 |
Financial instruments sold, not yet purchased | 44.4 | 22.5 |
Fair Value, Recurring | U.S. Treasury obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 442.7 | 419.9 |
Financial instruments sold, not yet purchased | 823.1 | 247.5 |
Fair Value, Recurring | U.S. government agency obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 274.9 | 293.4 |
Financial instruments sold, not yet purchased | 2.5 | 0.1 |
Fair Value, Recurring | Foreign government obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 3.7 | 2.5 |
Fair Value, Recurring | Agency mortgage-backed obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 1,738.8 | 1,384.6 |
Financial instruments sold, not yet purchased | 11.7 | 5.1 |
Fair Value, Recurring | Asset-backed obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 105.9 | 33.0 |
Fair Value, Recurring | Derivatives |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 198.0 | 117.4 |
Financial instruments sold, not yet purchased | 477.1 | 176.8 |
Fair Value, Recurring | Commodities leases |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 22.1 | 24.9 |
Financial instruments sold, not yet purchased | 1.1 | 1.1 |
Fair Value, Recurring | Commodities warehouse receipts |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 5.7 | 103.2 |
Fair Value, Recurring | Exchange firm common stock |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 12.8 | 10.1 |
Fair Value, Recurring | Mutual funds and other |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 9.8 | 7.5 |
Fair Value, Recurring | TBA and forward settling securities |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 21.6 | 19.2 |
Fair Value, Recurring | Foreign government obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 13.2 | 8.0 |
Fair Value, Recurring | U.S. Treasury obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 749.5 | 1,941.3 |
Fair Value, Recurring | Derivatives |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 244.5 | (192.7) |
Fair Value, Recurring | Commodities warehouse receipts |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Cash and securities segregated under federal and other regulation | 18.8 | 2.4 |
Fair Value, Recurring | U.S. Treasury obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Cash and securities segregated under federal and other regulation | 77.3 | 0.2 |
Fair Value, Recurring | Certificates of deposit |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Assets | 5.3 | 3.2 |
Fair Value, Recurring | Money market mutual funds |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Assets | 14.9 | 12.8 |
Fair Value, Recurring | Netting |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Cash and cash equivalents | 0.0 | 0.0 |
Cash and securities segregated under federal and other regulation | 0.0 | 0.0 |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | (4,120.0) | (2,549.3) |
Receivables from clients - Derivatives | (335.4) | (234.1) |
Financial instruments owned | (715.4) | (535.6) |
Total assets at fair value | (5,170.8) | (3,319.0) |
Payables to clients - Derivatives | (4,659.3) | (2,399.9) |
Financial instruments sold, not yet purchased | (592.4) | (386.8) |
Total liabilities at fair value | (5,308.7) | (3,100.7) |
Fair Value, Recurring | Netting | TBA and forward settling securities |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Payable to broker-dealers, clearing organizations and counterparties | (4.1) | (11.8) |
Fair Value, Recurring | Netting | Derivatives |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Payable to broker-dealers, clearing organizations and counterparties | (52.9) | (302.2) |
Fair Value, Recurring | Netting | Payables to Broker-dealers, Clearing Organizations and Counterparties |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Payable to broker-dealers, clearing organizations and counterparties | (57.0) | (314.0) |
Fair Value, Recurring | Netting | Contingent Consideration |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Accounts payable and other accrued liabilities - contingent liabilities | 0.0 | 0.0 |
Fair Value, Recurring | Netting | Physical commodities inventory |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Physical commodities inventory | 0.0 | 0.0 |
Fair Value, Recurring | Netting | Equity securities |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Netting | Corporate and municipal bonds |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Netting | U.S. Treasury obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Netting | U.S. government agency obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Netting | Foreign government obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Fair Value, Recurring | Netting | Agency mortgage-backed obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Netting | Asset-backed obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Fair Value, Recurring | Netting | Derivatives |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | (715.4) | (535.6) |
Financial instruments sold, not yet purchased | (592.4) | (386.8) |
Fair Value, Recurring | Netting | Commodities leases |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Netting | Commodities warehouse receipts |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Fair Value, Recurring | Netting | Exchange firm common stock |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Fair Value, Recurring | Netting | Mutual funds and other |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Fair Value, Recurring | Netting | TBA and forward settling securities |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 0.0 | (11.8) |
Fair Value, Recurring | Netting | Foreign government obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 0.0 | 0.0 |
Fair Value, Recurring | Netting | U.S. Treasury obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 0.0 | 0.0 |
Fair Value, Recurring | Netting | Derivatives |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | (4,120.0) | (2,537.5) |
Fair Value, Recurring | Netting | Commodities warehouse receipts |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Cash and securities segregated under federal and other regulation | 0.0 | 0.0 |
Fair Value, Recurring | Netting | U.S. Treasury obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Cash and securities segregated under federal and other regulation | 0.0 | 0.0 |
Fair Value, Recurring | Netting | Certificates of deposit |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Assets | 0.0 | 0.0 |
Fair Value, Recurring | Netting | Money market mutual funds |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Assets | 0.0 | 0.0 |
Fair Value, Recurring | Level 1 |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Cash and cash equivalents | 20.2 | 16.0 |
Cash and securities segregated under federal and other regulation | 96.1 | 2.6 |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 4,878.1 | 3,898.3 |
Receivables from clients - Derivatives | 0.0 | 0.0 |
Financial instruments owned | 959.5 | 798.8 |
Total assets at fair value | 6,089.0 | 4,742.5 |
Payables to clients - Derivatives | 3,858.6 | 2,000.8 |
Financial instruments sold, not yet purchased | 1,232.0 | 465.5 |
Total liabilities at fair value | 5,090.6 | 2,466.3 |
Fair Value, Recurring | Level 1 | TBA and forward settling securities |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Payable to broker-dealers, clearing organizations and counterparties | 0.0 | 0.0 |
Fair Value, Recurring | Level 1 | Derivatives |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Payable to broker-dealers, clearing organizations and counterparties | 0.0 | 0.0 |
Fair Value, Recurring | Level 1 | Payables to Broker-dealers, Clearing Organizations and Counterparties |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Payable to broker-dealers, clearing organizations and counterparties | 0.0 | 0.0 |
Fair Value, Recurring | Level 1 | Contingent Consideration |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Accounts payable and other accrued liabilities - contingent liabilities | 0.0 | 0.0 |
Fair Value, Recurring | Level 1 | Physical commodities inventory |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Physical commodities inventory | 135.1 | 26.8 |
Fair Value, Recurring | Level 1 | Equity securities |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 484.1 | 254.9 |
Financial instruments sold, not yet purchased | 397.7 | 218.0 |
Fair Value, Recurring | Level 1 | Corporate and municipal bonds |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Level 1 | U.S. Treasury obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 442.7 | 419.9 |
Financial instruments sold, not yet purchased | 823.1 | 247.5 |
Fair Value, Recurring | Level 1 | U.S. government agency obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Level 1 | Foreign government obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 3.7 | 2.5 |
Fair Value, Recurring | Level 1 | Agency mortgage-backed obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.2 | 0.0 |
Fair Value, Recurring | Level 1 | Asset-backed obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.2 | 0.0 |
Fair Value, Recurring | Level 1 | Derivatives |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.5 | 0.7 |
Financial instruments sold, not yet purchased | 11.0 | 0.0 |
Fair Value, Recurring | Level 1 | Commodities leases |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Level 1 | Commodities warehouse receipts |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 5.7 | 103.2 |
Fair Value, Recurring | Level 1 | Exchange firm common stock |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 12.8 | 10.1 |
Fair Value, Recurring | Level 1 | Mutual funds and other |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 9.8 | 7.5 |
Fair Value, Recurring | Level 1 | TBA and forward settling securities |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 0.0 | 0.0 |
Fair Value, Recurring | Level 1 | Foreign government obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 13.2 | 8.0 |
Fair Value, Recurring | Level 1 | U.S. Treasury obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 749.5 | 1,941.3 |
Fair Value, Recurring | Level 1 | Derivatives |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 4,115.4 | 1,949.0 |
Fair Value, Recurring | Level 1 | Commodities warehouse receipts |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Cash and securities segregated under federal and other regulation | 18.8 | 2.4 |
Fair Value, Recurring | Level 1 | U.S. Treasury obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Cash and securities segregated under federal and other regulation | 77.3 | 0.2 |
Fair Value, Recurring | Level 1 | Certificates of deposit |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Assets | 5.3 | 3.2 |
Fair Value, Recurring | Level 1 | Money market mutual funds |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Assets | 14.9 | 12.8 |
Fair Value, Recurring | Level 2 |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Cash and cash equivalents | 0.0 | 0.0 |
Cash and securities segregated under federal and other regulation | 0.0 | 0.0 |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 270.7 | 426.8 |
Receivables from clients - Derivatives | 340.5 | 235.6 |
Financial instruments owned | 3,223.1 | 2,464.5 |
Total assets at fair value | 4,075.5 | 3,315.8 |
Payables to clients - Derivatives | 305.0 | 176.4 |
Financial instruments sold, not yet purchased | 1,124.6 | 607.3 |
Total liabilities at fair value | 1,499.0 | 1,112.4 |
Fair Value, Recurring | Level 2 | TBA and forward settling securities |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Payable to broker-dealers, clearing organizations and counterparties | 16.5 | 22.0 |
Fair Value, Recurring | Level 2 | Derivatives |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Payable to broker-dealers, clearing organizations and counterparties | 52.9 | 306.7 |
Fair Value, Recurring | Level 2 | Payables to Broker-dealers, Clearing Organizations and Counterparties |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Payable to broker-dealers, clearing organizations and counterparties | 69.4 | 328.7 |
Fair Value, Recurring | Level 2 | Contingent Consideration |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Accounts payable and other accrued liabilities - contingent liabilities | 0.0 | 0.0 |
Fair Value, Recurring | Level 2 | Physical commodities inventory |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Physical commodities inventory | 241.2 | 188.9 |
Fair Value, Recurring | Level 2 | Equity securities |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 18.2 | 9.4 |
Financial instruments sold, not yet purchased | 6.6 | 14.9 |
Fair Value, Recurring | Level 2 | Corporate and municipal bonds |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 150.5 | 66.9 |
Financial instruments sold, not yet purchased | 44.4 | 22.5 |
Fair Value, Recurring | Level 2 | U.S. Treasury obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Level 2 | U.S. government agency obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 274.9 | 293.4 |
Financial instruments sold, not yet purchased | 2.5 | 0.1 |
Fair Value, Recurring | Level 2 | Foreign government obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Fair Value, Recurring | Level 2 | Agency mortgage-backed obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 1,738.8 | 1,384.6 |
Financial instruments sold, not yet purchased | 11.5 | 5.1 |
Fair Value, Recurring | Level 2 | Asset-backed obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 105.7 | 33.0 |
Fair Value, Recurring | Level 2 | Derivatives |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 912.9 | 652.3 |
Financial instruments sold, not yet purchased | 1,058.5 | 563.6 |
Fair Value, Recurring | Level 2 | Commodities leases |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 22.1 | 24.9 |
Financial instruments sold, not yet purchased | 1.1 | 1.1 |
Fair Value, Recurring | Level 2 | Commodities warehouse receipts |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Fair Value, Recurring | Level 2 | Exchange firm common stock |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Fair Value, Recurring | Level 2 | Mutual funds and other |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Fair Value, Recurring | Level 2 | TBA and forward settling securities |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 21.6 | 31.0 |
Fair Value, Recurring | Level 2 | Foreign government obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 0.0 | 0.0 |
Fair Value, Recurring | Level 2 | U.S. Treasury obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 0.0 | 0.0 |
Fair Value, Recurring | Level 2 | Derivatives |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 249.1 | 395.8 |
Fair Value, Recurring | Level 2 | Commodities warehouse receipts |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Cash and securities segregated under federal and other regulation | 0.0 | 0.0 |
Fair Value, Recurring | Level 2 | U.S. Treasury obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Cash and securities segregated under federal and other regulation | 0.0 | 0.0 |
Fair Value, Recurring | Level 2 | Certificates of deposit |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Assets | 0.0 | 0.0 |
Fair Value, Recurring | Level 2 | Money market mutual funds |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Assets | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Cash and cash equivalents | 0.0 | 0.0 |
Cash and securities segregated under federal and other regulation | 0.0 | 0.0 |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 0.0 | 0.0 |
Receivables from clients - Derivatives |  |  |
Financial instruments owned | 0.0 | 0.0 |
Total assets at fair value | 0.0 | 0.0 |
Payables to clients - Derivatives |  |  |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Total liabilities at fair value | 0.4 | 1.5 |
Fair Value, Recurring | Level 3 | TBA and forward settling securities |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Payable to broker-dealers, clearing organizations and counterparties | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Derivatives |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Payable to broker-dealers, clearing organizations and counterparties | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Payables to Broker-dealers, Clearing Organizations and Counterparties |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Payable to broker-dealers, clearing organizations and counterparties | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Contingent Consideration |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Accounts payable and other accrued liabilities - contingent liabilities | 0.4 | 1.5 |
Fair Value, Recurring | Level 3 | Physical commodities inventory |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Physical commodities inventory | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Equity securities |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Corporate and municipal bonds |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | U.S. Treasury obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | U.S. government agency obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Foreign government obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Agency mortgage-backed obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Asset-backed obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Derivatives |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Commodities leases |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Financial instruments sold, not yet purchased | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Commodities warehouse receipts |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Exchange firm common stock |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Mutual funds and other |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financial instruments owned | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | TBA and forward settling securities |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Foreign government obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | U.S. Treasury obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Derivatives |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Commodities warehouse receipts |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Cash and securities segregated under federal and other regulation | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | U.S. Treasury obligations |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Cash and securities segregated under federal and other regulation | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Certificates of deposit |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Assets | 0.0 | 0.0 |
Fair Value, Recurring | Level 3 | Money market mutual funds |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Assets | $ 0.0 | $ 0.0 |

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