Note 2 - Summary of Significant Accounting Policies - Remaining Performance Obligations 2 (Details)	Jun. 30, 2019 USD ($)
Revenue, Remaining Performance Obligation, Amount	$ 2,525,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-07-01
Revenue, Remaining Performance Obligation, Amount	$ 708,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	182 days
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Amount	$ 800,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Amount	$ 516,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Amount	$ 179,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Amount	$ 322,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Service [Member]
Revenue, Remaining Performance Obligation, Amount	$ 2,274,000
Service [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-07-01
Revenue, Remaining Performance Obligation, Amount	$ 701,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	182 days
Service [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Amount	$ 786,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Service [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Amount	$ 502,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Service [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Amount	$ 165,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Service [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Amount	$ 120,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Clinical Revenue [Member]
Revenue, Remaining Performance Obligation, Amount	$ 251,000
Clinical Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-07-01
Revenue, Remaining Performance Obligation, Amount	$ 7,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	182 days
Clinical Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Amount	$ 14,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Clinical Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Amount	$ 14,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Clinical Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Amount	$ 14,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Clinical Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Amount	$ 202,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year