Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 387	$ 373	$ 199
Securities available for sale:
Unrealized gains (losses) arising during the period, net of tax expense (benefit) of $16, $5 and $3	57	(17)	(6)
Reclassification adjustment for gains included in net income, net of tax expense of $0, $0 and $0	0	0	0
Derivative instruments:
Unrealized losses arising during the period, net of tax benefit of $5, $1 and $0	(17)
Unrealized losses arising during the period, net of tax benefit of $5, $1 and $0		(2)	(1)
Reclassification adjustment for gains included in net income, net of tax expense of $0, $0 and $0	(2)
Reclassification adjustment for gains included in net income, net of tax expense of $0, $0 and $0		(2)	0
Pension and postretirement benefit obligations:
Unrealized gains (losses) arising during the period, net of tax expense (benefit) of $(1), $1 and $0	3	(2)	0
Other Comprehensive Income (Loss)	41	(23)	(7)
Comprehensive Income	$ 428	$ 350	$ 192