Income Taxes - Schedule of Components of Consolidated Statements of Income and Equity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income tax expense	$ 76	$ 134	$ 157
Net unrealized gains (losses) on pension and other postretirement plans	3	5	0
Net unrealized gains (losses) on securities available for sale	25	35	(16)
Net unrealized gains (losses) on cash flow hedges	3	5	(1)
Total	$ 107	$ 179	$ 140