Variable Interest Entities - Unconsolidated VIEs (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Unconsolidated Assets
Interest Bearing Deposits in Banks		$ 7,003		$ 6,289
Securities Available for Sale		17,807		16,314
Loans held for investment	[1]	87,587		86,507
Other Assets		9,378		9,620
Unconsolidated Liabilities
Other Liabilities		3,339		2,048
Unconsolidated VIEs
Unconsolidated Assets
Interest Bearing Deposits in Banks		26		26
Securities Available for Sale		28		28
Loans held for investment		234		217
Other Assets		2,403		2,412
Total Assets		2,691		2,683
Unconsolidated Liabilities
Other Liabilities		221		179
Total Liabilities		221		179
Maximum Exposure to Loss		2,752		2,748
Unconsolidated VIEs | LIHC investments
Variable Interest Entities
Liabilities Assumed		55	$ 23
Unconsolidated Assets
Interest Bearing Deposits in Banks		0		0
Securities Available for Sale		28		28
Loans held for investment		216		198
Other Assets		998		976
Total Assets		1,242		1,202
Unconsolidated Liabilities
Other Liabilities		207		165
Total Liabilities		207		165
Maximum Exposure to Loss		1,242		1,202
Unconsolidated VIEs | Leasing investments
Unconsolidated Assets
Interest Bearing Deposits in Banks		26		26
Securities Available for Sale		0		0
Loans held for investment		18		19
Other Assets		1,365		1,401
Total Assets		1,409		1,446
Unconsolidated Liabilities
Other Liabilities		14		14
Total Liabilities		14		14
Maximum Exposure to Loss		1,430		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		0		0
Other Assets		40		35
Total Assets		40		35
Unconsolidated Liabilities
Other Liabilities		0		0
Total Liabilities		0		0
Maximum Exposure to Loss		$ 80		$ 79

[1] Includes $343 million and $340 million at March 31, 2019 and December 31, 2018, respectively, for net unamortized (discounts) and premiums and deferred (fees) and costs.