Regulatory Requirements (Net Capital and Net Capital Requirements for CS&Co) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Net capital	$ 3,117,000	$ 3,700,000
Broker-Dealer, Minimum Net Capital Required, Aggregate Indebtedness Standard	1,000	250
2% of Aggregate Debit Balances	616,000	446,000
Net capital in excess of required net capital	2,501,000	$ 3,254,000
TDAC [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Net capital	4,040,000
Broker-Dealer, Minimum Net Capital Required, Aggregate Indebtedness Standard	1,500
2% of Aggregate Debit Balances	748,000
Net capital in excess of required net capital	3,292,000
TD Ameritrade [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Net capital	350,000
Broker-Dealer, Minimum Net Capital Required, Aggregate Indebtedness Standard	250
2% of Aggregate Debit Balances	0
Net capital in excess of required net capital	$ 350,000