Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 286	$ 387	$ 373
Securities available for sale:
Unrealized gains (losses) arising during the period, net of tax expense (benefit) of $15, $16 and $(5)	54	57	(17)
Derivative instruments:
Unrealized losses arising during the period, net of tax benefit of $(11), $(5) and $(1)	(40)	(17)	(2)
Reclassification adjustment for gains (losses) included in net income, net of tax expense (benefit) of $3, $0 and $0	18	(2)	(2)
Pension and postretirement benefit obligations:
Unrealized gains (losses) arising during the period, net of tax expense (benefit) of $2, $(1) and $1	(6)	3	(2)
Other Comprehensive Income (Loss)	26	41	(23)
Comprehensive Income	$ 312	$ 428	$ 350