Credit Quality And Allowance For Credit Losses (Changes In The Allowance For Credit Losses On Lending-Related Commitments) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for credit losses on lending-related commitments		$ 60	$ 26	$ 47	$ 14	$ 2	$ 5	$ 11	$ 9	$ 147	$ 27	$ 46
Lending-related commitments
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period					$ 41				$ 36	41	36	32
Charge-offs on lending related commitments	[1]									(1)	0	0
Provision for credit losses on lending-related commitments										5	5	4
Balance at end of period		$ 45				$ 41				$ 45	$ 41	$ 36

[1] (a) Charge-offs result from the sale of unfunded lending-related commitments.