Note 7 - Revenues (Details Textual) g in Millions, T in Millions	Sep. 30, 2018 g T
Fixed Priced Contracts [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Revenue, Remaining Performance Obligation, Mass | T	0.3
Fixed Priced Contracts [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Mass | g	1.2
Contracts with Indexed Based Pricing Mechanisms [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Revenue, Remaining Performance Obligation, Mass | T	0.1
Contracts with Indexed Based Pricing Mechanisms [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Mass | g	0.3