Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net income for the period	$ 168	$ 114	$ 308	$ 204
Other comprehensive income, net of tax:
Unrealized holding gains on investment securities	61	33	73	65
Net unrealized gains (losses) on other noninterest-bearing investments	1	(1)	2	0
Net unrealized holding gains on derivative instruments	1	4	0	17
Reclassification adjustment for increase in interest income recognized in earnings on derivatives instruments	(1)	(1)	(2)	(3)
Pension and Postretirement	0	0	0	(1)
Other comprehensive income	62	35	73	78
Comprehensive income	$ 230	$ 149	$ 381	$ 282