Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net income for the period	$ 160	$ 127	$ 469	$ 332
Other comprehensive income, net of tax:
Unrealized holding gains (losses) on investment securities	(8)	(11)	65	54
Net unrealized gains on other noninterest-bearing investments	0	2	2	2
Net unrealized holding gains (losses) on derivative instruments	0	(3)	0	14
Reclassification adjustment for increase in interest income recognized in earnings on derivatives instruments	0	(2)	(2)	(5)
Pension and Postretirement	0	0	0	(1)
Other comprehensive income (loss)	(8)	(14)	65	64
Comprehensive income	$ 152	$ 113	$ 534	$ 396