Regulatory Capital and Other Regulatory Matters (Schedule of Regulatory Capital Amount and Ratios) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity tier one capital ratio	4.50%
Tier one capital to risk-weighted assets, required minimum	6.00%
Capital to risk-weighted assets, required minimum	8.00%
Capital conservation buffer	2.50%
Tier one leverage ratio, minimum	4.00%
BHC enhanced prudential standards, minimum	$ 100,000
BHC enhanced prudential standards, maximum	250,000
BHC stress test threshold	$ 50,000
BHC capital requirement, dividend payout ratio	30.00%
Minimum capital conservation buffer	2.50%	1.875%
Parent company
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity tier one capital	$ 13,603	$ 13,397
Common equity tier one capital ratio	9.33%	9.14%
Tier one capital to risk-weighted assets, amount	$ 16,035	$ 15,831
Tier one capital to risk-weighted assets, ratio	10.99%	10.80%
Capital to risk-weighted assets, amount	$ 18,292	$ 18,046
Capital to risk-weighted assets, ratio	12.54%	12.31%
Tier one leverage to adjusted quarterly average assets, amount	$ 16,035	$ 15,831
Tier one leverage to adjusted quarterly average assets, ratio	9.02%	9.00%
Subsidiaries
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity tier one capital	$ 16,609	$ 16,552
Common equity tier one capital ratio	12.55%	12.61%
Tier one capital to risk-weighted assets, amount	$ 16,609	$ 16,552
Tier one capital to risk-weighted assets, ratio	12.55%	12.61%
Capital to risk-weighted assets, amount	$ 17,802	$ 17,620
Capital to risk-weighted assets, ratio	13.46%	13.42%
Tier one leverage to adjusted quarterly average assets, amount	$ 16,609	$ 16,552
Tier one leverage to adjusted quarterly average assets, ratio	10.45%	10.69%
Required minimum | Parent company
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity tier one capital ratio	4.50%
Tier one capital to risk-weighted assets, required minimum	6.00%
Capital to risk-weighted assets, required minimum	8.00%
Tier one leverage ratio, minimum	4.00%
Required minimum | Subsidiaries
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity tier one capital ratio	4.50%
Tier one capital to risk-weighted assets, required minimum	6.00%
Capital to risk-weighted assets, required minimum	8.00%
Tier one leverage ratio, minimum	4.00%
Well-capitalized minimum | Parent company
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier one capital to risk-weighted assets, well-capitalized minimum	6.00%
Capital to risk weighted assets, well-capitalzed minimum	10.00%
Well-capitalized minimum | Subsidiaries
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity tier one capital ratio	6.50%
Tier one capital to risk-weighted assets, well-capitalized minimum	8.00%
Capital to risk weighted assets, well-capitalzed minimum	10.00%
Tier one leverage to adjusted quarterly average assets, well-capitalized minimum	5.00%