Investment Securities - Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value of Securities Available for Sale and Held to Maturity (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Available for sale securities
Amortized Cost	$ 66,698	$ 89,704
Gross Unrealized Gains	3	1
Gross Unrealized Losses	4,393	6,711
Fair Value	62,308	82,994
Unallocated portfolio layer method (PLM) fair value basis adjustments, Amortized Cost	8	(47)
Unallocated portfolio layer method fair value basis adjustments, Gross Unrealized Gains	0	0
Unallocated portfolio layer method fair value basis adjustments, Gross Unrealized Losses	8	(47)
Held to maturity securities
Amortized Cost	136,693	146,453
Gross Unrealized Gains	1,672	146
Gross Unrealized Losses	10,106	13,994
Fair Value	128,259	132,605
U.S. agency mortgage-backed securities
Available for sale securities
Amortized Cost	48,011	57,262
Gross Unrealized Gains	0	0
Gross Unrealized Losses	3,555	5,429
Fair Value	44,456	51,833
Held to maturity securities
Amortized Cost	136,693	146,453
Gross Unrealized Gains	1,672	146
Gross Unrealized Losses	10,106	13,994
Fair Value	128,259	132,605
U.S. Treasury securities
Available for sale securities
Amortized Cost	8,009	14,939
Gross Unrealized Gains	3	1
Gross Unrealized Losses	226	471
Fair Value	7,786	14,469
Corporate debt securities
Available for sale securities
Amortized Cost	5,502	10,166
Gross Unrealized Gains	0	0
Gross Unrealized Losses	411	587
Fair Value	5,091	9,579
Asset-backed securities
Available for sale securities
Amortized Cost	4,429	6,106
Gross Unrealized Gains	0	0
Gross Unrealized Losses	148	196
Fair Value	4,281	5,910
U.S. state and municipal securities
Available for sale securities
Amortized Cost	597	603
Gross Unrealized Gains	0	0
Gross Unrealized Losses	35	54
Fair Value	562	549
Foreign government agency securities
Available for sale securities
Amortized Cost		533
Gross Unrealized Gains		0
Gross Unrealized Losses		6
Fair Value		527
Non-agency commercial mortgage-backed securities
Available for sale securities
Amortized Cost	121	121
Gross Unrealized Gains	0	0
Gross Unrealized Losses	8	12
Fair Value	113	109
Other
Available for sale securities
Amortized Cost	21	21
Gross Unrealized Gains	0	0
Gross Unrealized Losses	2	3
Fair Value	$ 19	$ 18
Corporate Debt Securities Issued By Financial Services Industry \| Asset-backed securities \| Financial Instrument Concentration Risk
Held to maturity securities
Concentration (percent)	15.00%	35.00%
Corporate Debt Securities Issued By Information Technology Industry \| Asset-backed securities \| Financial Instrument Concentration Risk
Held to maturity securities
Concentration (percent)	25.00%	16.00%
Corporate Debt Securities Issued By Consumer Staples Industry \| Asset-backed securities \| Financial Instrument Concentration Risk
Held to maturity securities
Concentration (percent)	24.00%	18.00%
Federal Family Education Loan Program (FFELP) Guaranteed Loans \| Asset-backed securities \| Financial Instrument Concentration Risk
Held to maturity securities
Concentration (percent)	71.00%	62.00%
Collateralized Credit Card Securities \| Asset-backed securities \| Financial Instrument Concentration Risk
Held to maturity securities
Concentration (percent)	21.00%	25.00%

SCHWAB CHARLES CORP 10-Q