Other Borrowings (Details) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Line of Credit Facility [Line Items]
FHLB advances		$ 0	$ 500
Trust preferred securities		0	410
Total other borrowings		0	910
Redemption of Trust Preferred Securities		413	0	$ 0
Losses on early extinguishment of debt	$ 58	4	58	$ 0
Issuance of debt		420
E TRADE Securities [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		1,300
Line of Credit Facility, Fair Value of Amount Outstanding		0
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 300
Line of Credit Facility, Fair Value of Amount Outstanding		0
Revolving Credit Facility [Member] | Revolving credit facility maturing June 2019 [Member] | E TRADE Securities [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 600
Secured Committed Line of Credit [Member] | E TRADE Securities [Member]
Line of Credit Facility [Line Items]
Lines of Credit. Number of Creditors		2
Secured Committed Line of Credit [Member] | Line Of Credit Maturing June 2019 [Member] | E TRADE Securities [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 175
Unsecured Uncommitted Line of Credit [Member] | E TRADE Securities [Member]
Line of Credit Facility [Line Items]
Lines of Credit. Number of Creditors		3
Line of Credit Facility, Maximum Borrowing Capacity		$ 125
Unsecured Uncommitted Line of Credit [Member] | Line Of Credit Maturing June 2019 [Member] | E TRADE Securities [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		50
Secured Uncommitted Line of Credit [Member] | E TRADE Securities [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 375