Percentage of additional equity interest allowed to be purchased.

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The amount of operating losses on equity investments.

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No definition available.

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This element represents the distribution to minority investment partner accounted for under the equity method of accounting.

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Amount of income (loss) for foreign currency translations for equity method investment.

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Amount of aggregate decrease of financial instrument classified as an asset of level 3 of the fair value hierarchy.

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Amount of to cash distribution of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of decrease of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing due to other.

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Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy due to due to conversion of convertible debt.

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No definition available.

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Gain upon conversion of debt instrument.

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The amount of increase (decrease) in equity method investments during the period.

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Fair value portion of shares that an entity is required to redeem for cash or other assets at a fixed or determinable date or upon the occurrence of an event.

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No definition available.

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This element represents the aggregate cost of investments accounted for under the equity method of accounting.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Amount of investment in equity security without readily determinable fair value.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

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Amount of income (loss) for proportionate share of equity method investee's income (loss).

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The amount deducted from an entities' taxes, reflecting a percentage of an amount invested in certain assets spread over the useful life of those assets; includes deferred investment tax credits.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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The cash outflow associated with the purchase of or advances to an equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

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The cash outflow associated with the acquisition of or advances to an entity that is related to it but not strictly controlled (for example, an unconsolidated subsidiary, affiliate, and joint venture or equity method investment) or the acquisition of an additional interest in a subsidiary (controlled entity).

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Value of new stock classified as temporary equity issued during the period.

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Value of outstanding derivative securities that permit the holder the right to purchase securities (usually equity) from the issuer at a specified price.

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FAIR VALUE MEASUREMENTS AND INVESTMENTS - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Jan. 31, 2021	Dec. 31, 2019
Fair value measurements
Payment for investment			$ 6,399	$ 2,768
(Gain) loss on equity investments			$ (647)	$ 3,360
Alaska communications
Fair value measurements
Percentage of additional equity interest			3.00%
Privately Held Investment
Fair value measurements
Payments to acquire equity method investment		$ 2,800
Ownership percentage		24.00%
Increase (decrease) in equity method investments			$ (2,600)
(Gain) loss on equity investments			1,600
Currency losses			1,000
Equity Security
Fair value measurements
Payment for investment			3,000
Gain from conversion			2,500
Investments	$ 16,500		16,500		$ 11,000
India solar operations
Fair value measurements
Payments to acquire equity method investment			3,400
Carrying value	14,200		14,200			$ 11,800
Increase (decrease) in equity method investments			2,400
Currency losses			200
Operating losses on equity investments			500
Distribution to minority investment partner			300
Other Assets \| Privately Held Investment
Fair value measurements
Carrying value	15,300		15,300		17,900
Redeemable Common Units
Fair value measurements
Issuance of redeemable units	22,640		22,640
Other investments
Fair value measurements
Decrease in fair value of level 3 investments			11,400
Transferring out of level 3			11,000
Fair value of the remaining level 3 investments			400
Cash distributions			800
Income recognized			400
Other investments \| Renewable energy partnership
Fair value measurements
Investment Tax Credit					12,000
Equity investments	2,000		2,000		2,300
Investment cost							$ 14,400
Carrying Value
Fair value measurements
Long-term debt	374,600		374,600		72,800
Carrying Value \| Other Assets \| Privately Held Investment
Fair value measurements
Investments	1,300		1,300		1,300
Level 2 \| Estimated Fair Value
Fair value measurements
Long-term debt	382,000		382,000		$ 73,300
Level 3 \| Alaska communications
Fair value measurements
Fair value of common units	22,600		22,600
Warrants value	$ 600		$ 600