INVESTMENTS (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013 item	Jun. 30, 2012	Jun. 30, 2013 item	Jun. 30, 2012	Dec. 31, 2012
Investments
Cash distributions received from partnerships treated as cost method investees	$ 3,800,000	$ 3,000,000	$ 7,800,000	$ 5,500,000
Cash distributions received from partnerships treated as equity method investees	3,900,000	2,900,000	8,000,000	6,500,000
Number of entity's investments which is accounted for using equity method	3		3
Investments
Cash surrender value of life insurance policies	2,115,000		2,115,000		2,045,000
Total	111,800,000		111,800,000		109,750,000
Summary of unaudited summarized income statement information
Total revenues	79,342,000	73,555,000	156,061,000	145,890,000
Income from operations	24,914,000	22,235,000	48,888,000	41,927,000
Net income before taxes	24,926,000	22,247,000	48,911,000	41,956,000
Net income	24,926,000	22,143,000	48,911,000	41,748,000
Summary of unaudited summarized balance sheet information
Current assets	58,650,000		58,650,000		49,982,000
Non-current assets	81,826,000		81,826,000		79,529,000
Current liabilities	15,798,000		15,798,000		15,417,000
Non-current liabilities	1,492,000		1,492,000		1,351,000
Partnership equity	123,186,000		123,186,000		112,734,000
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
GTE Mobilnet of Texas RSA #17 Limited Partnership
Investments
Ownership percentage of equity method investee	20.51%		20.51%
Investments
Equity method investments:	26,543,000		26,543,000		25,695,000
Pennsylvania RSA 6(I) Limited Partnership
Investments
Ownership percentage of equity method investee	16.6725%		16.6725%
Investments
Equity method investments:	7,434,000		7,434,000		7,286,000
Pennsylvania RSA 6(II) Limited Partnership
Investments
Ownership percentage of equity method investee	23.67%		23.67%
Investments
Equity method investments:	24,186,000		24,186,000		23,338,000
CoBank, ACB Stock
Investments
Cost method investments:	5,028,000		5,028,000		5,023,000
Other
Investments
Cost method investments:	430,000		430,000		430,000
CVIN, LLC
Investments
Ownership percentage of equity method investee	13.43%		13.43%
Additional capital investment			100,000
Investments
Equity method investments:	$ 1,664,000		$ 1,664,000		$ 1,533,000