Other Borrowings (Details) $ in Millions	6 Months Ended
	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Line of Credit Facility [Line Items]
Securities sold under agreements to repurchase	$ 400	$ 0
FHLB advances	200	0
Total repurchase agreements and FHLB advances	600	0
Trust preferred securities	409	409
Total other borrowings	1,009	$ 409
E TRADE Securities [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,100
Line of Credit Facility, Fair Value of Amount Outstanding	$ 0
Trust preferred securities
Line of Credit Facility [Line Items]
Debt instrument maturity year	2031
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 2018 [Member] | E TRADE Securities [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 450
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 2018 [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	2
Line of Credit Facility, Maximum Borrowing Capacity	$ 75
Unsecured Uncommitted Line of Credit [Member] | Line Of Credit Maturing June 2018 [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