Income and Other Taxes - Reconciliation of Statutory Tax Rate to Effective Tax Rate (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
U.S. federal statutory income tax rate	21.00%	21.00%	21.00%
Nondeductible expenses	(1.90%)	4.10%	1.30%
Effect of tax law changes	3.10%	(10.50%)	(4.60%)
Change in valuation allowance for deferred tax assets	2.00%	9.90%	2.00%
State taxes, net of federal benefit	(0.60%)	5.50%	3.50%
Audit and other tax return adjustments	5.60%	1.40%	0.60%
Tax-exempt income, credits and incentives	4.50%	(5.90%)	(2.10%)
Foreign rate differential adjusted for U.S. taxation of foreign profits	(0.90%)	(2.60%)	0.10%
Stock-based compensation	(0.20%)	2.30%	(0.30%)
Goodwill impairment	(29.10%)	0.00%	0.00%
Other	0.10%	0.20%	0.30%
Effective Income Tax Rate	3.60%	25.40%	21.80%
Income taxes to federal, foreign and state jurisdictions	$ 61	$ 32	$ 94