Stockholders' Equity (Narrative) (Details) - USD ($)				12 Months Ended
	Dec. 11, 2020	Oct. 06, 2020	Apr. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 30, 2019	Oct. 25, 2018
Class of Stock [Line Items]
Common stock, shares authorized (shares)				3,000,000,000	3,000,000,000
Preferred stock, par value (USD per share)				$ 0.01	$ 0.01
Shares repurchased (in shares)				0	55,000,000	22,000,000
Shares repurchased					$ 2,220,000,000	$ 1,000,000,000
Preferred stock, shares authorized (in shares)				9,940,000	9,940,000
TD Ameritrade [Member]
Class of Stock [Line Items]
Number of shares issued in acquisition (in shares)		586,000,000
Conversion of shares (in shares)		1.0837
Common Stock [Member]
Class of Stock [Line Items]
Number of shares issued (in shares)					0	0
Share repurchase, authorized amount							$ 4,000,000,000.0	$ 1,000,000,000.0
Common Stock [Member] | TD Ameritrade [Member]
Class of Stock [Line Items]
Number of shares issued in acquisition (in shares)		509,000,000
Common Stock [Member] | TD Ameritrade [Member] | TD Bank [Member]
Class of Stock [Line Items]
Number of shares issued in acquisition (in shares)		177,000,000
Maximum percentage of voting interest		9.90%
Depositary Shares [Member]
Class of Stock [Line Items]
Number of shares sold (in shares)	2,500,000		2,500,000
Ownership interest	1.00%		1.00%
Liquidation preference per share (USD per share)	$ 1,000		$ 1,000
Series H Preferred Stock [Member]
Class of Stock [Line Items]
Fixed rate	4.00%			4.00%
Preferred stock, par value (USD per share)	$ 0.01
Liquidation preference per share (USD per share)	$ 100,000			$ 100,000
Proceeds from offering	$ 2,470,000,000
Series G Preferred Stock [Member]
Class of Stock [Line Items]
Fixed rate			5.375%	5.375%
Preferred stock, par value (USD per share)			$ 0.01
Liquidation preference per share (USD per share)			$ 100,000	$ 100,000
Proceeds from offering			$ 2,470,000,000
Nonvoting Common Stock [Member]
Class of Stock [Line Items]
Common stock, shares authorized (shares)		300,000,000		300,000,000	300,000,000
Nonvoting Common Stock [Member] | TD Ameritrade [Member] | TD Bank [Member]
Class of Stock [Line Items]
Number of shares issued in acquisition (in shares)		77,000,000
Shares converted (in shares)		2,000,000
Number of shares held (in shares)				79,000,000