CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 111	$ 83	$ 306	$ 214
Securities available for sale:
Unrealized gains (losses) arising during the period, net of tax expense (benefit) of $(3), $(1), $(8) and $18	(10)	(3)	(29)	63
Derivative instruments:
Unrealized gains (losses) arising during the period, net of tax expense (benefit) of $0, $2, $1 and $(9)	(1)	8	3	(32)
Reclassification adjustment for gains included in net income, net of tax expense of $1, $1, $3 and $2	4	4	11	7
Pension and postretirement benefit obligations:
Unrealized gains arising during the period, net of tax expense of $1, $0, $1 and $0	1	0	2	1
Other Comprehensive Income (Loss)	(6)	9	(13)	39
Comprehensive Income	$ 105	$ 92	$ 293	$ 253