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Minority Investments - Additional Information (Detail) |  | 3 Months Ended | 9 Months Ended
--- | --- | --- | ---
Oct. 06, 2015 USD ($) | Jun. 30, 2015 USD ($) | Dec. 31, 2015 USD ($) Item | Dec. 31, 2014 USD ($)
Schedule Of Equity Method Investments [Line Items] |  |  |  |
Impairment of minority interest investment |  |  | $ 746,000 | $ 3,464,000
Net proceeds from sale of ownership interest |  |  | $ 2,155,000 | (644,000)
Tres Amigas |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |
Number of commonly interconnected power grids | Item |  |  | 3 |
Equity method investment, aggregate cost |  |  | $ 5,400,000 |
Percentage of ownership interest hold |  |  | 26.00% |
Impairment of minority interest investment |  | $ 746,000 | $ 746,000 |
Net proceeds from sale of ownership interest |  |  | (356,000) |
Blade Dynamics Ltd |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |
Impairment of minority interest investment |  |  |  | $ 3,500,000
Cost method investment, original cost |  |  | $ 8,000,000 |
Percentage of outstanding common stock | 100.00% |  |  |
Net proceeds from sale of ownership interest | $ 2,500,000 |  |  |
Milestone achievement period | 3 years |  |  |
Blade Dynamics Ltd | Maximum |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |
Additional proceeds receivable upon successful achievement of certain milestones | $ 1,600,000 |  |  |

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- Definition This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting and losses recognized for other than temporary impairments (OTTI) of the subject investments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (c)-(e) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27357-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7(c),9(a)) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27405-111563 + Details
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