Information About GCI LLC's Operating Segments (Reconciliation of Segment Adjusted OIBDA to Operating Income and Earnings (Loss) from Continuing Operations) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Segment Reporting [Abstract]
Consolidated segment Adjusted OIBDA	$ 14,088	$ (7,872)
Stock‑based compensation	(5,236)	(2,726)
Depreciation and amortization	(16,021)	(753)
Operating income (loss)	(7,169)	(11,351)
Interest expense	(7,673)	0
Share of earnings (loss) of affiliates, net	(2,492)	1,723
Realized and unrealized gains (losses) on financial instruments, net	(100,198)	737,552
Other, net	244	209
Earnings (loss) before income taxes	$ (117,288)	$ 728,133

Adjusted Operating Income (Loss) Before Depreciation And Amortization

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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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.

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Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

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Amount of the cost of borrowed funds accounted for as interest expense.

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The net result for the period of deducting operating expenses from operating revenues.

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Amount of income (expense) related to nonoperating activities, classified as other.

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