Regulatory Requirements - Net Capital and Net Capital Requirements (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
CS&Co
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Net capital	$ 6,227,000	$ 5,629,000
Minimum dollar requirement	250	250
2% of aggregate debit balances	1,146,000	1,069,000
Net capital in excess of required net capital	5,081,000	4,560,000
TDAC
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Net capital	3,144,000	3,634,000
Minimum dollar requirement	1,500	1,500
2% of aggregate debit balances	506,000	440,000
Net capital in excess of required net capital	2,638,000	3,194,000
TD Ameritrade, Inc.
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Net capital	566,000	444,000
Minimum dollar requirement	250	250
2% of aggregate debit balances	0	0
Net capital in excess of required net capital	$ 566,000	$ 444,000