Variable Interest Entities - Unconsolidated VIEs (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Unconsolidated Assets
Interest Bearing Deposits in Banks	$ 13,138		$ 7,184
Securities Available for Sale	16,670		17,789
Loans held for investment	84,974		88,213
Other Assets	9,481		10,200
Total assets	164,029	$ 173,233	170,810
Unconsolidated Liabilities
Other Liabilities	2,892		2,837
Total liabilities	147,088		154,443
Unconsolidated VIEs
Unconsolidated Assets
Securities Available for Sale	26		27
Loans held for investment	262		232
Other Assets	2,187		2,197
Total assets	2,475		2,456
Unconsolidated Liabilities
Other Liabilities	213		152
Total liabilities	213		152
Maximum Exposure to Loss	2,585		2,557
Unconsolidated VIEs | LIHC investments
Unconsolidated Assets
Total assets	1,154		1,118
Unconsolidated Liabilities
Total liabilities	209		148
Unconsolidated VIEs | Leasing investments
Unconsolidated Assets
Total assets	1,241		1,256
Unconsolidated Liabilities
Total liabilities	0		0
Unconsolidated VIEs | Other investments
Unconsolidated Assets
Total assets	80		82
Unconsolidated Liabilities
Total liabilities	4		4
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure [Member] | LIHC investments
Variable Interest Entities
Liabilities Assumed	79	$ 82
Unconsolidated Assets
Securities Available for Sale	26		27
Loans held for investment	262		219
Other Assets	866		872
Unconsolidated Liabilities
Other Liabilities	209		148
Maximum Exposure to Loss	1,154		1,118
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure [Member] | Leasing investments
Unconsolidated Assets
Securities Available for Sale	0		0
Loans held for investment	0		0
Other Assets	1,241		1,256
Unconsolidated Liabilities
Other Liabilities	0		0
Maximum Exposure to Loss	1,261		1,276
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure [Member] | Other investments
Unconsolidated Assets
Securities Available for Sale	0		0
Loans held for investment	0		13
Other Assets	80		69
Unconsolidated Liabilities
Other Liabilities	4		4
Maximum Exposure to Loss	$ 170		$ 163