Fair Value Disclosures - Financial Assets and Liabilities Not Recorded at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Financial assets:
HTM securities	$ 17,750	$ 18,530
Loans and leases HFI, net of ALLL	140,912	134,491
Financial liabilities:
Total deposits	159,915	149,124
Long-term debt	22,776	23,769
Carrying Amount
Financial assets:
HTM securities	17,750	18,530
Loans and leases HFI, net of ALLL	140,912	134,491
FDIC loss share receivable		285
Financial liabilities:
Total deposits	159,915	149,124
FDIC loss share payable		685
Long-term debt	22,776	23,769
Fair Value
Financial assets:
HTM securities	18,083	18,519
Loans and leases HFI, net of ALLL	142,058	134,728
FDIC loss share receivable		11
Financial liabilities:
Total deposits	160,090	149,300
FDIC loss share payable		676
Long-term debt	23,376	24,206
Level 2 | Fair Value
Financial assets:
HTM securities	18,083	18,519
Loans and leases HFI, net of ALLL	0	0
FDIC loss share receivable		0
Financial liabilities:
Total deposits	160,090	149,300
FDIC loss share payable		0
Long-term debt	23,376	24,206
Level 3 | Fair Value
Financial assets:
HTM securities	0	0
Loans and leases HFI, net of ALLL	142,058	134,728
FDIC loss share receivable		11
Financial liabilities:
Total deposits	0	0
FDIC loss share payable		676
Long-term debt	$ 0	$ 0