Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 95	$ 85	$ 189	$ 172
Securities available for sale:
Unrealized gains (losses) arising during the period, net of tax expense (benefit) of $9 and $(3), $16 and $(11)	30	(9)	54	(39)
Derivative instruments:
Unrealized (losses) gains arising during the period, net of tax (benefit) expense of $(4) and $1, $(6) and $2	(14)	2	(20)	6
Reclassification adjustment for (gains) losses included in net income, net of tax expense (benefit) of $0, $0, $0 and $0	0	(1)	(1)	(1)
Pension and postretirement benefit obligations:
Unrealized gains (losses) arising during the period, net of tax expense (benefit) of $0, $0, $0 and $0	0	1	1	1
Other Comprehensive Income (Loss)	16	(7)	34	(33)
Comprehensive Income	$ 111	$ 78	$ 223	$ 139