Regulatory Requirements (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total assets	$ 607,548	$ 549,009
Charles Schwab Premier Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total assets	35,600
Trust Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total assets	$ 14,700