Summary of Significant Accounting Policies (Details) (USD $)	3 Months Ended								10 Months Ended	12 Months Ended			24 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012	Dec. 31, 2009
Summary of Significant Accounting Policies [Abstract]
Number of States in which Entity Operates	5								5	5			5
Number of miles of fiber network (in miles)										4,100
Number of business segments										3
Grants awarded by NTIA Broadband Technology Opportunity Program										$ 16,800,000
Periodic estimated investment on project										7,200,000
Periodic estimated investment on project (in hundredths)										30.00%
Approximate amount of capital expenditure for advanced high-capacity broadband network										24,000,000
Project completion period (in years)										3 years
Percentage of investment in property plant and equipment (in hundredths)										30.00%
Capital expenditure incurred										7,081,000	12,664,000		19,745,000
Capital expenditure recorded as an asset in property plant and equipment	5,923,000				3,799,000				5,923,000	5,923,000	3,799,000		5,923,000
NTIA reimbursements received										5,745,000	6,945,000		12,690,000
Capital expenditure pending reimbursement from NTIA	1,100,000				1,920,000				1,100,000	1,100,000	1,920,000		1,100,000
Variance of rate from median (in hundredths)										15.00%
Period of adjustment of costs and investments (in years)										2 years
Cash and cash equivalents	8,305,000				13,057,000				8,305,000	8,305,000	13,057,000	73,000	8,305,000	2,420,000
Maximum maturity period for classification as cash equivalents										3 months
Receivables, net of allowance for doubtful accounts	22,530,000				25,317,000				22,530,000	22,530,000	25,317,000		22,530,000
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of period				436,000				570,000		436,000	570,000	643,000	570,000
Additions charged to costs and expenses										290,000	299,000	1,010,000
Deductions										(448,000)	(433,000)	(1,083,000)
Balance at end of period	278,000				436,000				278,000	278,000	436,000	570,000	278,000
Investments [Abstract]
Non interest bearing subordinated capital certificates from RTFC	837,000				2,252,000				837,000	837,000	2,252,000		837,000
Non interest bearing subordinated capital certificates from CoBank	2,180,000				2,005,000				2,180,000	2,180,000	2,005,000		2,180,000
Investment in minority shares of cooperatives' equity	196,000				20,000				196,000	196,000	20,000		196,000
Property, Plant and Equipment [Line Items]
Interest costs capitalized										0
Components of property, plant and equipment [Abstract]
Total	437,623,000				397,140,000				437,623,000	437,623,000	397,140,000		437,623,000
Less: Accumulated depreciation and amortization	(254,664,000)				(242,886,000)				(254,664,000)	(254,664,000)	(242,886,000)		(254,664,000)
Property, plant and equipment, net	182,959,000				154,254,000				182,959,000	182,959,000	154,254,000	155,077,000	182,959,000
Composite depreciation rate (in hundredths)										3.30%	4.10%	4.10%
Depreciation expense										25,943,000	22,702,000	21,665,000
Capital leases assets, net	411,000				506,000				411,000	411,000	506,000		411,000
Capital leases assets, gross	2,405,000				2,272,000				2,405,000	2,405,000	2,272,000		2,405,000
Capital leases assets, accumulated depreciation	1,994,000				1,766,000				1,994,000	1,994,000	1,766,000		1,994,000
Capitalized software. amortized period (in years)										3 years
Capitalized cost										1,602,000	755,000	176,000
Capitalized software, amortization										936,000	675,000	568,000
Capitalized Computer Software, Net [Abstract]
Capitalized software for internal use, gross	11,578,000				9,976,000				11,578,000	11,578,000	9,976,000	9,385,000	11,578,000
Accumulated amortization	8,515,000				7,579,000				8,515,000	8,515,000	7,579,000	7,068,000	8,515,000
Net capitalized software for internal use	3,063,000				2,397,000				3,063,000	3,063,000	2,397,000	2,317,000	3,063,000
Minimum percentage of cumulative gains and losses considered for post-retirement benefits (in hundredths)										10.00%
Weighted average discount rate (in hundredths)	4.40%				4.40%				4.40%	4.40%	4.40%	5.40%	4.40%
Unrecognized net actuarial loss	6,760,000								6,760,000	6,760,000			6,760,000
Period over which recognized net actuarial loss is expected to be recognized										12 years
Defined Benefit Plan, Average Future Service										12 years
Percentage of realization of income tax (in hundredths)										50.00%
Advertising expense										871,000	908,000	909,000
Accrued incentive compensation	2,005,000				2,389,000				2,005,000	2,005,000	2,389,000		2,005,000
Earnings per share, basic and diluted [Abstract]
Net Income	2,525,000	1,741,000	1,738,000	2,294,000	1,574,000	2,133,000	2,348,000	2,346,000	939,000	8,298,000	8,401,000	12,592,000
Weighted average shares outstanding (in shares)										13,409,743	13,296,668	13,188,674
Total dilutive shares outstanding (in shares)										13,528,039	13,419,647	13,239,113
Earnings per share [Abstract]
Basic (in dollars per share)										$ 0.62	$ 0.63	$ 0.95
Diluted (in dollars per share)	$ 0.19	$ 0.13	$ 0.13	$ 0.17	$ 0.12	$ 0.16	$ 0.18	$ 0.18	$ 0.07	$ 0.61	$ 0.63	$ 0.95
Dividends per share (in dollars per share)	$ 0.145	$ 0.14	$ 0.14	$ 0.14	$ 0.14	$ 0.135	$ 0.135	$ 0.135		$ 0.565	$ 0.545	$ 0.525
Options excluded from computation of earnings per share amount (in shares)										77,150	169,450	308,250
Stock acquired and retired (in shares)											36,248
Stock Options (dilutive only) [Member]
Earnings per share, basic and diluted [Abstract]
Effect of dilutive securities (in shares)										12,254	12,531	3,321
Stock Subscribed (ESPP) [Member]
Earnings per share, basic and diluted [Abstract]
Effect of dilutive securities (in shares)										2,185	0	0
Stock Subscribed LTEIP [Member]
Earnings per share, basic and diluted [Abstract]
Effect of dilutive securities (in shares)										72,441	86,549	39,813
Retention Awards [Member]
Earnings per share, basic and diluted [Abstract]
Retention awards (in shares)										31,416	23,899	7,305
Land [Member]
Components of property, plant and equipment [Abstract]
Total	1,102,000				1,074,000				1,102,000	1,102,000	1,074,000		1,102,000
Buildings [Member]
Components of property, plant and equipment [Abstract]
Total	21,142,000				22,271,000				21,142,000	21,142,000	22,271,000		21,142,000
Buildings [Member] | Minimum [Member]
Components of property, plant and equipment [Abstract]
Estimated useful lives										28 years
Buildings [Member] | Maximum [Member]
Components of property, plant and equipment [Abstract]
Estimated useful lives										40 years
Leasehold Improvements [Member]
Components of property, plant and equipment [Abstract]
Total	4,680,000				4,073,000				4,680,000	4,680,000	4,073,000		4,680,000
Leasehold Improvements [Member] | Minimum [Member]
Components of property, plant and equipment [Abstract]
Estimated useful lives										3 years
Leasehold Improvements [Member] | Maximum [Member]
Components of property, plant and equipment [Abstract]
Estimated useful lives										39 years
Network and Outside Plant Facilities [Member]
Components of property, plant and equipment [Abstract]
Total	366,097,000				329,230,000				366,097,000	366,097,000	329,230,000		366,097,000
Network and Outside Plant Facilities [Member] | Minimum [Member]
Components of property, plant and equipment [Abstract]
Estimated useful lives										3 years
Network and Outside Plant Facilities [Member] | Maximum [Member]
Components of property, plant and equipment [Abstract]
Estimated useful lives										50 years
Furniture, Fixtures and Equipment [Member]
Components of property, plant and equipment [Abstract]
Total	37,756,000				35,510,000				37,756,000	37,756,000	35,510,000		37,756,000
Furniture, Fixtures and Equipment [Member] | Minimum [Member]
Components of property, plant and equipment [Abstract]
Estimated useful lives										3 years
Furniture, Fixtures and Equipment [Member] | Maximum [Member]
Components of property, plant and equipment [Abstract]
Estimated useful lives										15 years
Construction in Progress [Member]
Components of property, plant and equipment [Abstract]
Total	6,846,000				4,982,000				6,846,000	6,846,000	4,982,000		6,846,000
Fiber and Data Segment [Member]
Inventories [Abstract]
Inventories, raw materials	665,000				950,000				665,000	665,000	950,000		665,000
Components of property, plant and equipment [Abstract]
Property, plant and equipment, net	94,375,000				59,858,000				94,375,000	94,375,000	59,858,000	54,732,000	94,375,000
Earnings per share, basic and diluted [Abstract]
Net Income										5,933,000	4,423,000	4,603,000
Equipment Segment [Member]
Inventories [Abstract]
Inventories, finished goods with title	6,201,000				6,631,000				6,201,000	6,201,000	6,631,000		6,201,000
Components of property, plant and equipment [Abstract]
Property, plant and equipment, net	1,430,000				1,383,000				1,430,000	1,430,000	1,383,000	1,140,000	1,430,000
Earnings per share, basic and diluted [Abstract]
Net Income										1,523,000	1,651,000	1,348,000
Telecom Segment [Member]
Inventories [Abstract]
Inventories, raw materials	1,513,000				1,716,000				1,513,000	1,513,000	1,716,000		1,513,000
Components of property, plant and equipment [Abstract]
Property, plant and equipment, net	87,092,000				92,888,000				87,092,000	87,092,000	92,888,000	99,037,000	87,092,000
Earnings per share, basic and diluted [Abstract]
Net Income										$ 4,618,000	$ 6,776,000	$ 6,652,000