Interest Income and Interest Expense (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Interest income:
Cash and cash equivalents	$ 2	$ 1
Cash required to be segregated under federal or other regulation	1	0
Available-for-sale securities	64	66
Held-to-maturity securities	103	88
Margin receivables	64	68
Loans	51	62
Broker-related receivables and other	0	1
Subtotal interest income	285	286
Other interest revenue(1)	23	30
Total interest income	308	316
Interest expense:
Deposits	(1)	(2)
Customer payables	(1)	(1)
Other borrowings(2)	(5)	(41)
Corporate debt	(13)	(20)
Subtotal interest expense	(20)	(64)
Other interest expense(3)	(1)	(2)
Total interest expense	(21)	(66)
Net interest income (4)	$ 287	$ 250
Termination of legacy wholesale funding obligations			$ 4,400