Variable Interest Entities - Unconsolidated VIEs (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Unconsolidated Assets
Interest Bearing Deposits in Banks		$ 8,465		$ 6,289
Securities Available for Sale		17,251		16,314
Loans held for investment	[1]	88,693		86,507
Other Assets		10,002		9,620
Unconsolidated Liabilities
Other Liabilities		2,948		2,048
Unconsolidated VIEs
Unconsolidated Assets
Interest Bearing Deposits in Banks		0		26
Securities Available for Sale		27		28
Loans held for investment		236		217
Other Assets		2,329		2,412
Total Assets		2,592		2,683
Unconsolidated Liabilities
Other Liabilities		212		179
Total Liabilities		212		179
Maximum Exposure to Loss		2,697		2,748
Unconsolidated VIEs | LIHC investments
Variable Interest Entities
Liabilities Assumed		82	$ 45
Unconsolidated Assets
Interest Bearing Deposits in Banks		0		0
Securities Available for Sale		27		28
Loans held for investment		221		198
Other Assets		964		976
Total Assets		1,212		1,202
Unconsolidated Liabilities
Other Liabilities		208		165
Total Liabilities		208		165
Maximum Exposure to Loss		1,212		1,202
Unconsolidated VIEs | Leasing investments
Unconsolidated Assets
Interest Bearing Deposits in Banks		0		26
Securities Available for Sale		0		0
Loans held for investment		0		19
Other Assets		1,297		1,401
Total Assets		1,297		1,446
Unconsolidated Liabilities
Other Liabilities		0		14
Total Liabilities		0		14
Maximum Exposure to Loss		1,332		1,467
Unconsolidated VIEs | Other investments
Unconsolidated Assets
Interest Bearing Deposits in Banks		0		0
Securities Available for Sale		0		0
Loans held for investment		15		0
Other Assets		68		35
Total Assets		83		35
Unconsolidated Liabilities
Other Liabilities		4		0
Total Liabilities		4		0
Maximum Exposure to Loss		$ 153		$ 79

[1] Includes $335 million and $340 million at September 30, 2019 and December 31, 2018, respectively, for net unamortized (discounts) and premiums and deferred (fees) and costs.