Consolidated Investment Products (CIP) - Fair Value Hierarchy Levels Of Investments Held And Notes Issued By Consolidated Investment Products (Details) - USD ($) $ in Millions | Sep. 30, 2020 | Dec. 31, 2019 |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Total assets at fair value | $ 7,718.4 | $ 7,808 |
Significant Unobservable Inputs (Level 3) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Total assets at fair value | | 78.6 |
Bank loans | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 6,596.8 | |
Consolidated | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Real estate investments | | 78.6 |
Total assets at fair value | 7,718.4 | 7,808 |
Consolidated | Quoted Prices in Active Markets for Identical Assets (Level 1) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Real estate investments | | 0 |
Total assets at fair value | 202.8 | 225.2 |
Consolidated | Significant Other Observable Inputs (Level 2) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Real estate investments | | 0 |
Total assets at fair value | 7,273 | 7,290.8 |
Consolidated | Significant Unobservable Inputs (Level 3) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Real estate investments | | 78.6 |
Total assets at fair value | 0 | 78.6 |
Consolidated | Investments Measured at NAV as a practical expedient | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Real estate investments | | 0 |
Total assets at fair value | 242.6 | 213.4 |
Consolidated | Bank loans | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 6,616.6 | 6,504.4 |
Consolidated | Bank loans | Quoted Prices in Active Markets for Identical Assets (Level 1) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 0 | 0 |
Consolidated | Bank loans | Significant Other Observable Inputs (Level 2) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 6,616.6 | 6,504.4 |
Consolidated | Bank loans | Significant Unobservable Inputs (Level 3) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 0 | 0 |
Consolidated | Bank loans | Investments Measured at NAV as a practical expedient | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 0 | 0 |
Consolidated | Bonds | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 550.3 | 705.9 |
Consolidated | Bonds | Quoted Prices in Active Markets for Identical Assets (Level 1) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 0 | 0.5 |
Consolidated | Bonds | Significant Other Observable Inputs (Level 2) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 550.3 | 705.4 |
Consolidated | Bonds | Significant Unobservable Inputs (Level 3) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 0 | 0 |
Consolidated | Bonds | Investments Measured at NAV as a practical expedient | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 0 | 0 |
Consolidated | Equity securities, Equity and fixed income mutual funds | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 278 | 275.9 |
Equity and fixed income mutual funds, and investments in other private equity funds | 23.3 | 29.8 |
Consolidated | Equity securities, Equity and fixed income mutual funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 202.4 | 204.4 |
Equity and fixed income mutual funds, and investments in other private equity funds | 0.4 | 20.3 |
Consolidated | Equity securities, Equity and fixed income mutual funds | Significant Other Observable Inputs (Level 2) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 75.6 | 71.5 |
Equity and fixed income mutual funds, and investments in other private equity funds | 22.9 | 9.5 |
Consolidated | Equity securities, Equity and fixed income mutual funds | Significant Unobservable Inputs (Level 3) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 0 | 0 |
Equity and fixed income mutual funds, and investments in other private equity funds | 0 | 0 |
Consolidated | Equity securities, Equity and fixed income mutual funds | Investments Measured at NAV as a practical expedient | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 0 | 0 |
Equity and fixed income mutual funds, and investments in other private equity funds | 0 | 0 |
Consolidated | Investments in other private equity funds | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Equity and fixed income mutual funds, and investments in other private equity funds | 250.2 | 213.4 |
Consolidated | Investments in other private equity funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Equity and fixed income mutual funds, and investments in other private equity funds | 0 | 0 |
Consolidated | Investments in other private equity funds | Significant Other Observable Inputs (Level 2) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Equity and fixed income mutual funds, and investments in other private equity funds | 7.6 | 0 |
Consolidated | Investments in other private equity funds | Significant Unobservable Inputs (Level 3) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Equity and fixed income mutual funds, and investments in other private equity funds | 0 | 0 |
Consolidated | Investments in other private equity funds | Investments Measured at NAV as a practical expedient | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Equity and fixed income mutual funds, and investments in other private equity funds | $ 242.6 | $ 213.4 |