Note 2 - Revenue Recognition - Disaggregated Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Sales	$ 3,363	$ 2,666	$ 2,560
Gas Utilities [Member]
Sales	1,263	1,008	832
Downstream [Member]
Sales	1,009	783	786
Upstream [Member]
Sales	707	542	600
Midstream [Member]
Sales	384	333	342
UNITED STATES
Sales	2,823	2,178	2,023
UNITED STATES | Gas Utilities [Member]
Sales	1,247	995	821
UNITED STATES | Downstream [Member]
Sales	758	560	566
UNITED STATES | Upstream [Member]
Sales	458	321	329
UNITED STATES | Midstream [Member]
Sales	360	302	307
CANADA
Sales	166	132	128
CANADA | Gas Utilities [Member]
Sales	15	13	11
CANADA | Downstream [Member]
Sales	25	20	15
CANADA | Upstream [Member]
Sales	117	88	89
CANADA | Midstream [Member]
Sales	9	11	13
International [Member]
Sales	374	356	409
International [Member] | Gas Utilities [Member]
Sales	1	0	0
International [Member] | Downstream [Member]
Sales	226	203	205
International [Member] | Upstream [Member]
Sales	132	133	182
International [Member] | Midstream [Member]
Sales	$ 15	$ 20	$ 22