INVESTMENTS (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014 item	Jun. 30, 2013	Jun. 30, 2014 item	Jun. 30, 2013	Dec. 31, 2013
Investments
Cash distributions received from partnerships treated as cost method investees	$ 3,800,000	$ 3,800,000	$ 7,300,000	$ 7,800,000
Cash distributions received from partnerships treated as equity method investees	4,900,000	3,900,000	10,500,000	8,000,000
Number of entity's investments which is accounted for using equity method	3		3
Investments
Cash surrender value of life insurance policies	1,965,000		1,965,000		2,183,000
Total	112,852,000		112,852,000		113,099,000
Summary of unaudited summarized income statement information
Total revenues	83,228,000	79,342,000	164,044,000	156,061,000
Income from operations	23,426,000	24,914,000	49,306,000	48,888,000
Net income before taxes	23,459,000	24,926,000	49,362,000	48,911,000
Net income	23,459,000	24,926,000	49,362,000	48,911,000
Summary of unaudited summarized balance sheet information
Current assets	48,715,000		48,715,000		54,837,000
Non-current assets	93,528,000		93,528,000		87,968,000
Current liabilities	14,624,000		14,624,000		15,221,000
Non-current liabilities	2,611,000		2,611,000		1,786,000
Partnership equity	125,008,000		125,008,000		125,799,000
GTE Mobilnet of South Texas Limited Partnership
Investments
Ownership percentage of cost method investee	2.34%		2.34%
Investments
Cost method investments:	21,450,000		21,450,000		21,450,000
Pittsburgh SMSA Limited Partnership
Investments
Ownership percentage of cost method investee	3.60%		3.60%
Investments
Cost method investments:	22,950,000		22,950,000		22,950,000
CoBank, ACB Stock
Investments
Cost method investments:	5,107,000		5,107,000		5,112,000
Other
Investments
Cost method investments:	200,000		200,000		200,000
GTE Mobilnet of Texas RSA #17 Limited Partnership
Investments
Ownership percentage of equity method investee	20.51%		20.51%
Investments
Equity method investments:	27,409,000		27,409,000		27,467,000
Pennsylvania RSA 6(I) Limited Partnership
Investments
Ownership percentage of equity method investee	16.6725%		16.6725%
Investments
Equity method investments:	7,548,000		7,548,000		7,696,000
Pennsylvania RSA 6(II) Limited Partnership
Investments
Ownership percentage of equity method investee	23.67%		23.67%
Investments
Equity method investments:	24,287,000		24,287,000		24,105,000
CVIN, LLC
Investments
Ownership percentage of equity method investee	12.089%		12.089%
Purchase of additional ownership interest				100,000
Investments
Equity method investments:	$ 1,936,000		$ 1,936,000		$ 1,936,000