Note 1 - Description of the Business and Summary of Significant Accounting Policies - Allowance for Expected Credit Losses (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Trade Accounts Receivable [Member]
Gross amortized cost	$ 10,756,000	$ 22,741,000
Allowance for credit losses
Amortized cost, net of allowance for credit losses	10,756,000	22,741,000
Account Receivables with Extended Payment Term Originated in 2020 [Member]
Gross amortized cost	3,009,000
Allowance for credit losses
Amortized cost, net of allowance for credit losses	3,009,000
Account Receivables with Extended Payment Term Originated in 2019 [Member]
Gross amortized cost	4,073,000	5,461,000
Allowance for credit losses
Amortized cost, net of allowance for credit losses	4,073	5,461
Account Receivables with Extended Payment Term [Member]
Gross amortized cost	7,082,000	5,461,000
Allowance for credit losses
Amortized cost, net of allowance for credit losses	7,082,000	5,461,000
Sales-type Leases Receivables Classified as Accounts Receivable Originated in 2019 [Member]
Gross amortized cost	1,772,000	2,206,000
Allowance for credit losses	(89,000)	(111,000)
Amortized cost, net of allowance for credit losses	1,683,000	2,095,000
Sales-type Leases Receivables Classified as Accounts Receivable Originated in 2017 [Member]
Gross amortized cost	42,000	52,000
Allowance for credit losses	(2,000)	(3,000)
Amortized cost, net of allowance for credit losses	40,000	49,000
Sales-type Leases Receivables Classified as Accounts Receivable [Member]
Gross amortized cost	1,814,000	2,258,000
Allowance for credit losses	(91,000)	(114,000)
Amortized cost, net of allowance for credit losses	1,723,000	2,144,000
Deposits and Other Originated in 2020 [Member]
Gross amortized cost	2,390,000
Allowance for credit losses
Amortized cost, net of allowance for credit losses	2,390,000
Development Agreements Classified as Deposits and Other Originated in 2019 [Member]
Gross amortized cost	2,431,000	2,359,000
Allowance for credit losses
Amortized cost, net of allowance for credit losses	2,431,000	2,359,000
Development Agreements Classified as Deposits and Other [Member]
Gross amortized cost	4,821,000	2,359,000
Allowance for credit losses
Amortized cost, net of allowance for credit losses	$ 4,821,000	$ 2,359,000