Note 11 - Retirement Plans - Pension Plan Fair Value Measurements (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined benefit plan, fair value of plan assets	$ 117	$ 104	$ 119
Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of plan assets	102	89
Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of plan assets	15	15
Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of plan assets	0	0
Insurance General Account [Member]
Defined benefit plan, fair value of plan assets	15	15
Insurance General Account [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of plan assets	0	0
Insurance General Account [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of plan assets	15	15
Insurance General Account [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of plan assets	0	0
Cash and Cash Equivalents [Member]
Defined benefit plan, fair value of plan assets	5	4
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of plan assets	5	4
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of plan assets	0	0
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of plan assets	0	0
Equity Securities [Member]
Defined benefit plan, fair value of plan assets	59	53
Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of plan assets	59	53
Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of plan assets	0	0
Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of plan assets	0	0
Fixed Income Securities [Member]
Defined benefit plan, fair value of plan assets	35	29
Fixed Income Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of plan assets	35	29
Fixed Income Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of plan assets	0	0
Fixed Income Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of plan assets	0	0
Real Estate [Member]
Defined benefit plan, fair value of plan assets	3	3
Real Estate [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of plan assets	3	3
Real Estate [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of plan assets	0	0
Real Estate [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of plan assets	$ 0	$ 0