Investment Securities - Hedge Funds and Private Equity Funds (Details) $ in Millions	Sep. 30, 2021 USD ($) fund	Dec. 31, 2020 USD ($)
Private equity funds
Debt and Equity Securities, FV-NI [Line Items]
Number of investments	14
Hedge funds
Debt and Equity Securities, FV-NI [Line Items]
Number of investments	1
Hedge and private equity funds included in other long-term investments
Debt and Equity Securities, FV-NI [Line Items]
Largest single fund investment | $	$ 27.4	$ 29.1