Regulatory Capital and Other Regulatory Matters (Schedule of Regulatory Capital Amount and Ratios) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jan. 10, 2018	Aug. 22, 2017	Jun. 28, 2017	Dec. 31, 2016	Jul. 19, 2016	Jun. 29, 2016
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 Capital Required for Capital Adequacy to Risk-weighted Assets	4.50%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%
Common equity Tier 1 capital conservation buffer	2.50%
Federal Reserve Bank Stock	$ 445					$ 435
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries	$ 400	$ 2,900
Minimum Capital Conservation Buffer	1.30%					0.63%
Increase in Minimum Capital Conservation Buffer	3.00%
Assets greater than $50 billion	$ 50,000
Increase (Decrease) in Dividends Payable	50.00%
FRB Approved Capital Action - Dividends					$ 0.12			$ 0.08
Increase (decrease) in share repurchase program	9.00%
Stock Repurchase Program, Authorized Amount					$ 760		$ 700
Increase (Decrease) in Dividends Payable, per share	$ 0.01		$ 0.01
2017 through 2018 [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Stock Repurchase Program, Authorized Amount	$ 760
Parent Company [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 Capital Required for Capital Adequacy to Risk-weighted Assets	4.50%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%
Common Equity Tier 1 Capital	$ 13,237					$ 12,978
Percentage of Common Equity Tier 1 Capital to Risk-weighted Assets	9.53%					9.37%
Tier One Risk Based Capital	$ 15,628					$ 15,147
Tier One Risk Based Capital to Risk Weighted Assets	11.25%					10.93%
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	6.00%
Capital	$ 17,974					$ 17,419
Capital to Risk Weighted Assets	12.94%					12.57%
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%
Tier One Leverage Capital	$ 15,628					$ 15,147
Tier One Leverage Capital to Average Assets	9.53%					9.54%
Subsidiaries [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 Capital Required for Capital Adequacy to Risk-weighted Assets	4.50%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%			15.00%
Common Equity Tier 1 Capital	$ 17,059					$ 17,888
Percentage of Common Equity Tier 1 Capital to Risk-weighted Assets	15.04%					16.70%
Common Equity Tier 1 Capital Required to be Well Capitalized to Risk-weighted Assets	6.50%
Tier One Risk Based Capital	$ 17,059					$ 17,888
Tier One Risk Based Capital to Risk Weighted Assets	15.04%					16.70%
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%
Capital	$ 17,886					$ 18,458
Capital to Risk Weighted Assets	15.77%					17.24%
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%
Tier One Leverage Capital	$ 17,059					$ 17,888
Tier One Leverage Capital to Average Assets	12.87%					15.21%
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%