The amount of the gain (loss) recognized by the parent and included in its attributable portion of net income for the period due to deconsolidation of a subsidiary or derecognition of a group of assets. The gain (loss) recognized and included in the net income attributable to the parent for the period is generally computed as the difference between: (a) the aggregate of: (1) the fair value of any consideration received; (2) the fair value of any retained noncontrolling investment in the former subsidiary at the date the subsidiary was deconsolidated; and (3) the carrying amount of any noncontrolling interest in the former subsidiary (including any accumulated other comprehensive income attributable to the noncontrolling interest) at the date the subsidiary was deconsolidated and (b) the carrying amount of the former subsidiary's assets and liabilities.

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-Name Accounting Standards Codification

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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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Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

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Total investments in (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable from a party that is affiliated with the reporting entity by means of direct or indirect ownership.

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Date the deconsolidation event occurred.

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Capital expenditures as a percentage of revenue, used as an input to measure fair value.

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Percentage of assumed frowth in revenues in the next ten years, used as an input to measure fair value.

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Investment in Unconsolidated Entities, Deconsolidation (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	Apr. 03, 2013
Deconsolidation of New York Partnerships
Investments in unconsolidated entities	$ 265,585,000	$ 283,014,000
St. Lawrence Seaway RSA Cellular Partnership
Deconsolidation of New York Partnerships
Ownership interest in equity method investment	60.00%
New York RSA 2 Cellular Partnership
Deconsolidation of New York Partnerships
Ownership interest in equity method investment	57.14%
St. Lawrence Seaway RSA Cellular Partnership and New York RSA 2 Cellular Partnership
Deconsolidation of New York Partnerships
Date of deconsolidation	Apr. 03, 2013
Investments in unconsolidated entities			114,800,000
Deconsolidation gain	$ 18,500,000
Discounted cash flow valuation approach \| St. Lawrence Seaway RSA Cellular Partnership and New York RSA 2 Cellular Partnership
Fair Value Inputs
Average expected revenue growth rate (next ten years)	2.00%
Terminal revenue growth rate (after year ten)	2.00%
Discount rate	10.50%
Discounted cash flow valuation approach \| Minimum \| St. Lawrence Seaway RSA Cellular Partnership and New York RSA 2 Cellular Partnership
Fair Value Inputs
Capital expenditures as a percentage of revenue	14.90%
Discounted cash flow valuation approach \| Maximum \| St. Lawrence Seaway RSA Cellular Partnership and New York RSA 2 Cellular Partnership
Fair Value Inputs
Capital expenditures as a percentage of revenue	18.80%