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Note 5 - Retirement Plans - Plan Assets Measured At Fair Value (Details) - Pension Plan [Member] - USD ($) $ in Millions | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | --- | ---
Plan Assets Fair Value |  | $ 4,363 | $ 5,554 | $ 5,016
Fair Value, Recurring [Member] |  |  |  |
Plan Assets Fair Value |  | 4,363 | 5,554 |
Fair Value, Recurring [Member] | Defined Benefit Plan, Debt Security [Member] |  |  |  |
Plan Assets Fair Value | [1] | 68 | 185 |
Fair Value, Recurring [Member] | Venture Capital And Buyout Partnerships [Member] |  |  |  |
Plan Assets Fair Value |  | 611 | 710 |
Fair Value, Recurring [Member] | Defined Benefit Plan, Real Estate [Member] |  |  |  |
Plan Assets Fair Value |  | 37 | 48 |
Fair Value, Recurring [Member] | Common Trust And Other Funds [Member] |  |  |  |
Plan Assets Fair Value |  | 622 | 756 |
Fair Value, Recurring [Member] | Other Assets Pension Plan [Member] |  |  |  |
Plan Assets Fair Value | [2] | 35 | (12) |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] |  |  |  |
Plan Assets Fair Value |  | 1,111 | 1,999 |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Cash [Member] |  |  |  |
Plan Assets Fair Value |  | 1 | 9 |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Equity Securities [Member] |  |  |  |
Plan Assets Fair Value | [3] | 6 | 10 |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member] |  |  |  |
Plan Assets Fair Value |  | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member] |  |  |  |
Plan Assets Fair Value |  | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Equity Securities, Common Stock [Member] |  |  |  |
Plan Assets Fair Value |  | 1,104 | 1,980 |
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] |  |  |  |
Plan Assets Fair Value |  | 1,879 | 1,868 |
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Cash [Member] |  |  |  |
Plan Assets Fair Value |  | 0 | 0 |
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Equity Securities [Member] |  |  |  |
Plan Assets Fair Value | [3] | 0 | 0 |
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member] |  |  |  |
Plan Assets Fair Value |  | 803 | 742 |
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member] |  |  |  |
Plan Assets Fair Value |  | 1,069 | 1,116 |
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Equity Securities, Common Stock [Member] |  |  |  |
Plan Assets Fair Value |  | 7 | 10 |
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] |  |  |  |
Plan Assets Fair Value |  | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Cash [Member] |  |  |  |
Plan Assets Fair Value |  | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Equity Securities [Member] |  |  |  |
Plan Assets Fair Value | [3] | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member] |  |  |  |
Plan Assets Fair Value |  | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member] |  |  |  |
Plan Assets Fair Value |  | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Equity Securities, Common Stock [Member] |  |  |  |
Plan Assets Fair Value |  | 0 | 0 |
Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] | Fair Value, Recurring [Member] |  |  |  |
Plan Assets Fair Value |  | 2,990 | 3,867 |
Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Cash [Member] |  |  |  |
Plan Assets Fair Value |  | 1 | 9 |
Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Equity Securities [Member] |  |  |  |
Plan Assets Fair Value | [3] | 6 | 10 |
Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member] |  |  |  |
Plan Assets Fair Value |  | 803 | 742 |
Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member] |  |  |  |
Plan Assets Fair Value |  | 1,069 | 1,116 |
Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Equity Securities, Common Stock [Member] |  |  |  |
Plan Assets Fair Value |  | 1,111 | 1,990 |
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] |  |  |  |
Plan Assets Fair Value |  | $ 1,338 | $ 1,699 |
[1] | Registered investment companies measured at NAV include bond investments.
[2] | Other assets include accrued receivables, net payables, and pending broker settlements.
[3] | Registered investment companies measured at fair value are stock investments.

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