Goodwill and Acquired Intangible Assets (Changes in Carrying Amount of Goodwill as Allocated to Reportable Segments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Goodwill [Roll Forward]
Beginning balance	$ 11,952	$ 1,227
Goodwill acquired and other changes during the period	0
Ending balance	11,952	11,952
TD Ameritrade Holding [Member]
Goodwill [Roll Forward]
Goodwill acquired		10,215
Other Acquisitions [Member]
Goodwill [Roll Forward]
Goodwill acquired		510
Investor Services [Member]
Goodwill [Roll Forward]
Beginning balance	7,970	1,096
Goodwill acquired and other changes during the period	0
Ending balance	7,970	7,970
Investor Services [Member] | TD Ameritrade Holding [Member]
Goodwill [Roll Forward]
Goodwill acquired		6,380
Investor Services [Member] | Other Acquisitions [Member]
Goodwill [Roll Forward]
Goodwill acquired		494
Advisor Services [Member]
Goodwill [Roll Forward]
Beginning balance	3,982	131
Goodwill acquired and other changes during the period	0
Ending balance	$ 3,982	3,982
Advisor Services [Member] | TD Ameritrade Holding [Member]
Goodwill [Roll Forward]
Goodwill acquired		3,835
Advisor Services [Member] | Other Acquisitions [Member]
Goodwill [Roll Forward]
Goodwill acquired		$ 16