Note 2 - Revenue Recognition - Disaggregated Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Sales	$ 585	$ 942	$ 1,981	$ 2,896
UNITED STATES
Sales	463	763	1,575	2,348
CANADA
Sales	27	57	105	183
International [Member]
Sales	95	122	301	365
Gas Utilities [Member]
Sales	208	216	615	677
Gas Utilities [Member] | UNITED STATES
Sales	206	215	605	663
Gas Utilities [Member] | CANADA
Sales	2	1	10	14
Gas Utilities [Member] | International [Member]
Sales	0	0	0	0
Downstream [Member]
Sales	185	285	612	861
Downstream [Member] | UNITED STATES
Sales	131	218	447	667
Downstream [Member] | CANADA
Sales	4	7	12	18
Downstream [Member] | International [Member]
Sales	50	60	153	176
Upstream [Member]
Sales	118	287	474	883
Upstream [Member] | UNITED STATES
Sales	61	189	266	583
Upstream [Member] | CANADA
Sales	17	43	72	130
Upstream [Member] | International [Member]
Sales	40	55	136	170
Midstream [Member]
Sales	74	154	280	475
Midstream [Member] | UNITED STATES
Sales	65	141	257	435
Midstream [Member] | CANADA
Sales	4	6	11	21
Midstream [Member] | International [Member]
Sales	$ 5	$ 7	$ 12	$ 19