Borrowings and Contractual Commitments Contractual Commitments (Details) $ in Millions	Dec. 31, 2017 USD ($)
Long-term Purchase Commitment [Line Items]
Other Commitment	$ 25,265
Other Commitment, Due in Second Year	9,648
Other Commitment, Due in Third Year	13,773
Other Commitment, Due in Fourth Year	13,380
Other Commitment, Due in Fifth Year	15,879
Other Commitment, Due after Fifth Year	12,066
Other Commitment	90,011
Purchase Obligation, Due in Next Twelve Months	278	[1]
Purchase Obligation, Due in Second Year	260	[1]
Purchase Obligation, Due in Third Year	76	[1]
Purchase Obligation, Due in Fourth Year	50	[1]
Purchase Obligation, Due in Fifth Year	48	[1]
Purchase Obligation, Due after Fifth Year	247	[1]
Purchase Obligation	959	[1]
Qualified Affordable Housing Project Investments, Commitment	690	[2]
consumer and other time [Member]
Long-term Purchase Commitment [Line Items]
Time Deposit Maturities, Next Twelve Months	4,720	[3],[4]
Time Deposit Maturities, Year Two	2,559	[3],[4]
Time Deposit Maturities, Year Three	1,331	[3],[4]
Time Deposit Maturities, Year Four	617	[3],[4]
Time Deposit Maturities, Year Five	834	[3],[4]
Time Deposit Maturities, after Year Five	2,015	[3],[4]
Time Deposits	12,076	[3],[4]
Brokered Time Deposits [Member]
Long-term Purchase Commitment [Line Items]
Time Deposit Maturities, Next Twelve Months	105	[3]
Time Deposit Maturities, Year Two	181	[3]
Time Deposit Maturities, Year Three	251	[3]
Time Deposit Maturities, Year Four	194	[3]
Time Deposit Maturities, Year Five	178	[3]
Time Deposit Maturities, after Year Five	76	[3]
Time Deposits	985	[3]
Year Two [Member]
Long-term Purchase Commitment [Line Items]
Qualified Affordable Housing Project Investments, Commitment	0	[2]
Year Three [Member]
Long-term Purchase Commitment [Line Items]
Qualified Affordable Housing Project Investments, Commitment	0	[2]
Year Four [Member]
Long-term Purchase Commitment [Line Items]
Qualified Affordable Housing Project Investments, Commitment	0	[2]
Year Five [Member]
Long-term Purchase Commitment [Line Items]
Qualified Affordable Housing Project Investments, Commitment	0	[2]
After Year Five [Member]
Long-term Purchase Commitment [Line Items]
Qualified Affordable Housing Project Investments, Commitment	$ 0	[2]

[1] For legally binding purchase obligations of $5 million or more, amounts include either termination fees under the associated contracts when early termination provisions exist, or the total potential obligation over the full contractual term for noncancelable purchase obligations. Payments made towards the purchase of goods or services under these contracts totaled $395 million, $236 million, and $243 million in 2017, 2016, and 2015, respectively.

[2] Commitments to fund investments in affordable housing and other partnerships do not have defined funding dates as certain criteria must be met before the Company is obligated to fund. Accordingly, these commitments are considered to be due on demand for presentation purposes. See Note 10, "Certain Transfers of Financial Assets and Variable Interest Entities," in this Form 10-K for additional information.

[3] Amounts do not include interest.

[4] The aggregate amount of time deposit accounts in denominations of $250,000 or more was $3.2 billion and $1.7 billion at December 31, 2017 and 2016, respectively.