Note 3 - Goodwill and Other Intangible Assets - Amortization Expense Related to Amortizable Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Charged to cost of sales	$ 2	$ 2	$ 7	$ 5
Charged to amortization of intangibles	4	4	11	10
Total amortization	$ 6	$ 6	$ 18	$ 15

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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