Fair Values of Assets and Liabilities (Fair Value of Other Financial Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Assets:
Held to maturity securities		$ 136,099
U.S. agency mortgage-backed securities [Member]
Assets:
Held to maturity securities		110,566
Corporate debt securities [Member]
Assets:
Held to maturity securities		4,718
Asset-backed securities [Member]
Assets:
Held to maturity securities		17,771
Non-agency commercial mortgage-backed securities [Member]
Assets:
Held to maturity securities		1,141
U.S. Treasury securities [Member]
Assets:
Held to maturity securities		228
Certificates of deposit [Member]
Assets:
Held to maturity securities		200
U.S. state and municipal securities [Member]
Assets:
Held to maturity securities		1,404
Foreign government agency securities [Member]
Assets:
Held to maturity securities		50
Reported Value Measurement [Member]
Assets:
Cash and cash equivalents	$ 29,189	21,668
Cash and investments segregated and on deposit for regulatory purposes	19,143	11,807
Receivables from brokerage clients — net	64,436	21,763
Held to maturity securities		134,706
Bank loans, net	23,813	18,212
Other assets	2,883	1,014
Liabilities:
Bank deposits	358,022	220,094
Payables to brokerage clients	104,201	39,220
Accrued expenses and other liabilities	8,263	1,882
Long-term debt	13,626	7,430
Reported Value Measurement [Member] | First Mortgage [Member]
Assets:
Bank loans, net	14,882	11,693
Reported Value Measurement [Member] | HELOC's [Member]
Assets:
Bank loans, net	837	1,113
Reported Value Measurement [Member] | Pledged asset lines [Member]
Assets:
Bank loans, net	7,916	5,206
Reported Value Measurement [Member] | Other [Member]
Assets:
Bank loans, net	178	200
Reported Value Measurement [Member] | U.S. agency mortgage-backed securities [Member]
Assets:
Held to maturity securities		109,325
Reported Value Measurement [Member] | Corporate debt securities [Member]
Assets:
Held to maturity securities		4,661
Reported Value Measurement [Member] | Asset-backed securities [Member]
Assets:
Held to maturity securities		17,806
Reported Value Measurement [Member] | Non-agency commercial mortgage-backed securities [Member]
Assets:
Held to maturity securities		1,119
Reported Value Measurement [Member] | U.S. Treasury securities [Member]
Assets:
Held to maturity securities		223
Reported Value Measurement [Member] | Certificates of deposit [Member]
Assets:
Held to maturity securities		200
Reported Value Measurement [Member] | U.S. state and municipal securities [Member]
Assets:
Held to maturity securities		1,301
Reported Value Measurement [Member] | Foreign government agency securities [Member]
Assets:
Held to maturity securities		50
Reported Value Measurement [Member] | Other [Member]
Assets:
Held to maturity securities		21
Portion at Other than Fair Value Measurement [Member]
Assets:
Cash and cash equivalents	29,189	21,668
Cash and investments segregated and on deposit for regulatory purposes	19,143	11,807
Receivables from brokerage clients — net	64,436	21,763
Held to maturity securities		136,099
Bank loans, net	24,237	18,198
Other assets	2,883	1,014
Liabilities:
Bank deposits	358,022	220,094
Payables to brokerage clients	104,201	39,220
Accrued expenses and other liabilities	8,263	1,882
Long-term debt	14,829	7,775
Portion at Other than Fair Value Measurement [Member] | First Mortgage [Member]
Assets:
Bank loans, net	15,305	11,639
Portion at Other than Fair Value Measurement [Member] | HELOC's [Member]
Assets:
Bank loans, net	838	1,153
Portion at Other than Fair Value Measurement [Member] | Pledged asset lines [Member]
Assets:
Bank loans, net	7,916	5,206
Portion at Other than Fair Value Measurement [Member] | Other [Member]
Assets:
Bank loans, net	178	200
Portion at Other than Fair Value Measurement [Member] | U.S. agency mortgage-backed securities [Member]
Assets:
Held to maturity securities		110,566
Portion at Other than Fair Value Measurement [Member] | Corporate debt securities [Member]
Assets:
Held to maturity securities		4,718
Portion at Other than Fair Value Measurement [Member] | Asset-backed securities [Member]
Assets:
Held to maturity securities		17,771
Portion at Other than Fair Value Measurement [Member] | Non-agency commercial mortgage-backed securities [Member]
Assets:
Held to maturity securities		1,141
Portion at Other than Fair Value Measurement [Member] | U.S. Treasury securities [Member]
Assets:
Held to maturity securities		228
Portion at Other than Fair Value Measurement [Member] | Certificates of deposit [Member]
Assets:
Held to maturity securities		200
Portion at Other than Fair Value Measurement [Member] | U.S. state and municipal securities [Member]
Assets:
Held to maturity securities		1,404
Portion at Other than Fair Value Measurement [Member] | Foreign government agency securities [Member]
Assets:
Held to maturity securities		50
Portion at Other than Fair Value Measurement [Member] | Other [Member]
Assets:
Held to maturity securities		21
Portion at Other than Fair Value Measurement [Member] | Level 1 [Member]
Assets:
Cash and cash equivalents	29,189	21,668
Cash and investments segregated and on deposit for regulatory purposes	4,212	2,792
Receivables from brokerage clients — net	0	0
Held to maturity securities		0
Bank loans, net	0	0
Other assets	0	0
Liabilities:
Bank deposits	0	0
Payables to brokerage clients	0	0
Accrued expenses and other liabilities	0	0
Long-term debt	0	0
Portion at Other than Fair Value Measurement [Member] | Level 1 [Member] | First Mortgage [Member]
Assets:
Bank loans, net	0	0
Portion at Other than Fair Value Measurement [Member] | Level 1 [Member] | HELOC's [Member]
Assets:
Bank loans, net	0	0
Portion at Other than Fair Value Measurement [Member] | Level 1 [Member] | Pledged asset lines [Member]
Assets:
Bank loans, net	0	0
Portion at Other than Fair Value Measurement [Member] | Level 1 [Member] | Other [Member]
Assets:
Bank loans, net	0	0
Portion at Other than Fair Value Measurement [Member] | Level 1 [Member] | U.S. agency mortgage-backed securities [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 1 [Member] | Corporate debt securities [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 1 [Member] | Asset-backed securities [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 1 [Member] | Non-agency commercial mortgage-backed securities [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 1 [Member] | U.S. Treasury securities [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 1 [Member] | Certificates of deposit [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 1 [Member] | U.S. state and municipal securities [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 1 [Member] | Foreign government agency securities [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 1 [Member] | Other [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 2 [Member]
Assets:
Cash and cash equivalents	0	0
Cash and investments segregated and on deposit for regulatory purposes	14,931	9,015
Receivables from brokerage clients — net	64,436	21,763
Held to maturity securities		136,099
Bank loans, net	24,237	18,198
Other assets	2,883	1,014
Liabilities:
Bank deposits	358,022	220,094
Payables to brokerage clients	104,201	39,220
Accrued expenses and other liabilities	8,263	1,882
Long-term debt	14,829	7,775
Portion at Other than Fair Value Measurement [Member] | Level 2 [Member] | First Mortgage [Member]
Assets:
Bank loans, net	15,305	11,639
Portion at Other than Fair Value Measurement [Member] | Level 2 [Member] | HELOC's [Member]
Assets:
Bank loans, net	838	1,153
Portion at Other than Fair Value Measurement [Member] | Level 2 [Member] | Pledged asset lines [Member]
Assets:
Bank loans, net	7,916	5,206
Portion at Other than Fair Value Measurement [Member] | Level 2 [Member] | Other [Member]
Assets:
Bank loans, net	178	200
Portion at Other than Fair Value Measurement [Member] | Level 2 [Member] | U.S. agency mortgage-backed securities [Member]
Assets:
Held to maturity securities		110,566
Portion at Other than Fair Value Measurement [Member] | Level 2 [Member] | Corporate debt securities [Member]
Assets:
Held to maturity securities		4,718
Portion at Other than Fair Value Measurement [Member] | Level 2 [Member] | Asset-backed securities [Member]
Assets:
Held to maturity securities		17,771
Portion at Other than Fair Value Measurement [Member] | Level 2 [Member] | Non-agency commercial mortgage-backed securities [Member]
Assets:
Held to maturity securities		1,141
Portion at Other than Fair Value Measurement [Member] | Level 2 [Member] | U.S. Treasury securities [Member]
Assets:
Held to maturity securities		228
Portion at Other than Fair Value Measurement [Member] | Level 2 [Member] | Certificates of deposit [Member]
Assets:
Held to maturity securities		200
Portion at Other than Fair Value Measurement [Member] | Level 2 [Member] | U.S. state and municipal securities [Member]
Assets:
Held to maturity securities		1,404
Portion at Other than Fair Value Measurement [Member] | Level 2 [Member] | Foreign government agency securities [Member]
Assets:
Held to maturity securities		50
Portion at Other than Fair Value Measurement [Member] | Level 2 [Member] | Other [Member]
Assets:
Held to maturity securities		21
Portion at Other than Fair Value Measurement [Member] | Level 3 [Member]
Assets:
Cash and cash equivalents	0	0
Cash and investments segregated and on deposit for regulatory purposes	0	0
Receivables from brokerage clients — net	0	0
Held to maturity securities		0
Bank loans, net	0	0
Other assets	0	0
Liabilities:
Bank deposits	0	0
Payables to brokerage clients	0	0
Accrued expenses and other liabilities	0	0
Long-term debt	0	0
Portion at Other than Fair Value Measurement [Member] | Level 3 [Member] | First Mortgage [Member]
Assets:
Bank loans, net	0	0
Portion at Other than Fair Value Measurement [Member] | Level 3 [Member] | HELOC's [Member]
Assets:
Bank loans, net	0	0
Portion at Other than Fair Value Measurement [Member] | Level 3 [Member] | Pledged asset lines [Member]
Assets:
Bank loans, net	0	0
Portion at Other than Fair Value Measurement [Member] | Level 3 [Member] | Other [Member]
Assets:
Bank loans, net	$ 0	0
Portion at Other than Fair Value Measurement [Member] | Level 3 [Member] | U.S. agency mortgage-backed securities [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 3 [Member] | Corporate debt securities [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 3 [Member] | Asset-backed securities [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 3 [Member] | Non-agency commercial mortgage-backed securities [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 3 [Member] | U.S. Treasury securities [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 3 [Member] | Certificates of deposit [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 3 [Member] | U.S. state and municipal securities [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 3 [Member] | Foreign government agency securities [Member]
Assets:
Held to maturity securities		0
Portion at Other than Fair Value Measurement [Member] | Level 3 [Member] | Other [Member]
Assets:
Held to maturity securities		$ 0