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Note 5 - Retirement Plans - Plan Assets Measured At Fair Value (Details) - Pension Plan [Member] - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | --- | ---
Plan Assets Fair Value |  | $ 5,554 | $ 5,016 | $ 4,528
Fair Value, Recurring [Member] |  |  |  |
Plan Assets Fair Value |  | 5,554 | 5,016 |
Fair Value, Recurring [Member] | Defined Benefit Plan, Debt Security [Member] |  |  |  |
Plan Assets Fair Value | [1] | 185 | 312 |
Fair Value, Recurring [Member] | Venture Capital And Buyout Partnerships [Member] |  |  |  |
Plan Assets Fair Value |  | 710 | 585 |
Fair Value, Recurring [Member] | Defined Benefit Plan, Real Estate [Member] |  |  |  |
Plan Assets Fair Value |  | 48 | 161 |
Fair Value, Recurring [Member] | Common Trust And Other Funds [Member] |  |  |  |
Plan Assets Fair Value |  | 756 | 498 |
Fair Value, Recurring [Member] | Other Assets Pension Plan [Member] |  |  |  |
Plan Assets Fair Value | [2] | (12) | 1 |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] |  |  |  |
Plan Assets Fair Value |  | 1,999 | 2,470 |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Cash [Member] |  |  |  |
Plan Assets Fair Value |  | 9 | 9 |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Equity Securities [Member] |  |  |  |
Plan Assets Fair Value | [3] | 10 | 252 |
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 |  | 1,980 | 2,209 |
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] |  |  |  |
Plan Assets Fair Value |  | 1,868 | 989 |
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 |  | 742 | 150 |
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member] |  |  |  |
Plan Assets Fair Value |  | 1,116 | 831 |
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Equity Securities, Common Stock [Member] |  |  |  |
Plan Assets Fair Value |  | 10 | 8 |
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, 2 and 3 [Member] | Fair Value, Recurring [Member] |  |  |  |
Plan Assets Fair Value |  | 3,867 | 3,459 |
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Cash [Member] |  |  |  |
Plan Assets Fair Value |  | 9 | 9 |
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Equity Securities [Member] |  |  |  |
Plan Assets Fair Value | [3] | 10 | 252 |
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member] |  |  |  |
Plan Assets Fair Value |  | 742 | 150 |
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member] |  |  |  |
Plan Assets Fair Value |  | 1,116 | 831 |
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Fair Value, Recurring [Member] | Defined Benefit Plan, Equity Securities, Common Stock [Member] |  |  |  |
Plan Assets Fair Value |  | 1,990 | 2,217 |
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] |  |  |  |
Plan Assets Fair Value |  | $ 1,699 | $ 1,556 |
[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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