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Represents the amount of proceeds received during the period from payments on accounts receivable that were overdue.

+ References

No definition available.

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Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable.

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Face (par) amount of debt instrument at time of issuance.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount of the required periodic payments including both interest and principal payments.

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Amount of payment greater than the preceding installment payments to be paid at final maturity date of debt.

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The adjustment to expense previously capitalized costs of drilling exploratory wells when proved reserves are not found or when the entity obtains information that raises substantial doubt about the economic or operational viability of the project.

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Amount of cash inflow for proceeds from settlement of insurance claim, classified as operating activities. Excludes insurance settlement classified as investing activities.

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Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

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Note 1 - General and Basis of Presentation 1 (Details Textual) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended		12 Months Ended
	Mar. 25, 2019	Apr. 30, 2019	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Jan. 04, 2019
Exploration Abandonment and Impairment Expense			$ 0	$ 123
Accounts Receivable, after Allowance for Credit Loss, Current, Total			139,870		$ 137,581
Product [Member]
Revenue, Remaining Performance Obligation, Amount			226,100
Kenya Power and Lighting Co LTD [Member]
Accounts Receivable, Past Due			29,400
ENNE [Member]
Accounts Receivable, Past Due			$ 18,000
Accounts Receivable [Member] \| Customer Concentration Risk [Member] \| Primary Customers [Member]
Concentration Risk, Percentage			55.00%		56.00%
Revenue Benchmark [Member] \| Customer Concentration Risk [Member] \| Sierra Pacific Power Company And Nevada Power Company [Member]
Concentration Risk, Percentage			18.20%	17.40%
Revenue Benchmark [Member] \| Customer Concentration Risk [Member] \| Southern California Public Power Authority [Member]
Concentration Risk, Percentage			19.40%	16.30%
Revenue Benchmark [Member] \| Customer Concentration Risk [Member] \| Kenya Power and Lighting Co LTD [Member]
Concentration Risk, Percentage			15.30%	15.10%
Revenue Benchmark [Member] \| Customer Concentration Risk [Member] \| Pacific Gas & Electric [Member]
Concentration Risk, Percentage			1.20%
UNITED STATES
Cash, Cash Equivalents, and Short-term Investments, Total			$ 28,600		$ 31,300
Foreign Countries [Member]
Cash, Cash Equivalents, and Short-term Investments, Total			75,900		93,900
Accounts Receivable, after Allowance for Credit Loss, Current, Total			106,800		$ 102,000
DEG 3 Loan Agreement [Member]
Debt Instrument, Interest Rate, Stated Percentage						6.04%
DEG 3 Loan Agreement [Member] \| OrPower 4, Inc [Member]
Debt Instrument, Face Amount						$ 41,500
Additional Migdal Loan [Member]
Debt Instrument, Face Amount	$ 50,000
Debt Instrument, Interest Rate, Stated Percentage	4.60%
Debt Instrument, Periodic Payment, Total	$ 2,100
Debt Instrument, Periodic Payment Terms, Balloon Payment to be Paid	$ 18,500
Subsequent Event [Member] \| Kenya Power and Lighting Co LTD [Member]
Proceeds, Overdue Accounts Receivable		$ 20,400
Subsequent Event [Member] \| ENNE [Member]
Proceeds, Overdue Accounts Receivable		3,000
Electricity Segment [Member] \| Puna Geothermal Power Plant [Member]
Proceeds from Insurance Settlement, Operating Activities			1,500
Electricity Segment [Member] \| Puna Geothermal Power Plant [Member] \| Subsequent Event [Member]
Proceeds from Insurance Settlement, Operating Activities		$ 4,100
Electricity Segment [Member] \| Puna Geothermal Power Plant [Member] \| Cost of Sales [Member]
Proceeds from Insurance Settlement, Operating Activities			$ 1,300