Note 10 - Income Taxes (Details Textual) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Effective Income Tax Rate Reconciliation, Percent, Total	33.30%	(11.20%)	35.50%	14.50%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			21.00%
Foreign Tax Authority [Member] | Kenya Revenue Authority [Member] | First and Second Assessment Tax Years 2013-2017 [Member]
Income Tax Examination, Assessment	$ 157		$ 157
Income Tax Examination, Penalties and Interest Accrued, Total	42		42
Foreign Tax Authority [Member] | Kenya Revenue Authority [Member] | Third Assessment Tax Years 2013-2017 [Member]
Income Tax Examination, Assessment	3		3
Income Tax Examination, Penalties and Interest Accrued, Total	$ 1		$ 1