Goodwill And Other Intangible Assets (Amortizing Intangible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 195	$ 195
Accumulated amortization	(193)	(187)
Net carrying amount	2	8
Goodwill impairment	0	0
Core Deposit Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	167	167
Accumulated amortization	(165)	(159)
Net carrying amount	2	8
Customer Relationships And Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	28	28
Accumulated amortization	(28)	(28)
Net carrying amount	$ 0	$ 0