Note 11 - Retirement Plans - Pension Plan Fair Value Measurements (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined benefit plan, fair value of plan assets	$ 119	$ 108	$ 97
Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of plan assets	104	92
Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of plan assets	15	16
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	16
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	16
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	3	3
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of plan assets	3	3
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	52
Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of plan assets	59	52
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	39	35
Fixed Income Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of plan assets	39	35
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	2
Real Estate [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of plan assets	3	2
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