Subsequent Events (Details) - USD ($)	Oct. 06, 2020	Oct. 31, 2020	Oct. 05, 2020	Sep. 30, 2020	Dec. 31, 2019
Subsequent Event [Line Items]
Common stock, shares authorized (shares)				3,000,000,000	3,000,000,000
Insured Deposit Account Agreement Member [Member] | TD and its affiliates [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Basis spread on variable rate	0.15%		0.25%
Floating rate investment floor	$ 20,000,000,000
Reduction in deposit balance over 12 month period	10,000,000,000
Floor amount	$ 50,000,000,000
Percentage of fixed rate investments	80.00%
Renewal term	5 years
Prior written notice period for termination	2 years
Common Stock - Nonvoting [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Common stock, shares authorized (shares)	300,000,000
TD Ameritrade [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of shares issued in acquisition (in shares)	586,000,000
TD Ameritrade [Member] | Common Stock [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of shares issued in acquisition (in shares)	509,000,000
TD Ameritrade [Member] | Common Stock [Member] | TD Bank [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of shares issued in acquisition (in shares)	177,000,000
Maximum percentage common stock interest	9.90%
TD Ameritrade [Member] | Common Stock - Nonvoting [Member] | TD Bank [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of shares issued in acquisition (in shares)	77,000,000
Number of shares exchanged (in shares)	2,000,000
Number of shares held (in shares)		79,000,000