BENEFIT PLANS (Details) (USD $)	12 Months Ended				12 Months Ended																																																																																																																																																						12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2009	Dec. 31, 2010	Dec. 31, 2012 Other Deferred Compensation Arrangement [Member]	Dec. 31, 2011 Other Deferred Compensation Arrangement [Member]	Dec. 31, 2010 Other Deferred Compensation Arrangement [Member]	Dec. 31, 2012 Employee Stock Ownership Plan 401K Plan [Member]	Dec. 31, 2011 Employee Stock Ownership Plan 401K Plan [Member]	Dec. 31, 2010 Employee Stock Ownership Plan 401K Plan [Member]	Dec. 31, 2012 Money Market Accounts [Member]	Dec. 31, 2011 Money Market Accounts [Member]	Dec. 31, 2012 Money Market Accounts [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2011 Money Market Accounts [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2012 Money Market Accounts [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2011 Money Market Accounts [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2012 Money Market Accounts [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2011 Money Market Accounts [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2012 Equity Securities [Member]	Dec. 31, 2011 Equity Securities [Member]	Dec. 31, 2012 Equity Securities [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2011 Equity Securities [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2012 Equity Securities [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2011 Equity Securities [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2012 Equity Securities [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2011 Equity Securities [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2012 U.S Large-Cap [Member]	Dec. 31, 2011 U.S Large-Cap [Member]	Dec. 31, 2012 U.S Large-Cap [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2011 U.S Large-Cap [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2012 U.S Large-Cap [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2011 U.S Large-Cap [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2012 U.S Large-Cap [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2011 U.S Large-Cap [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2012 U.S Mid/Small Cap [Member]	Dec. 31, 2011 U.S Mid/Small Cap [Member]	Dec. 31, 2012 U.S Mid/Small Cap [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2011 U.S Mid/Small Cap [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2012 U.S Mid/Small Cap [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2011 U.S Mid/Small Cap [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2012 U.S Mid/Small Cap [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2011 U.S Mid/Small Cap [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2012 CBSI Stock [Member]	Dec. 31, 2011 CBSI Stock [Member]	Dec. 31, 2012 CBSI Stock [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2011 CBSI Stock [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2012 CBSI Stock [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2011 CBSI Stock [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2012 CBSI Stock [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2011 CBSI Stock [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2012 International [Member]	Dec. 31, 2011 International [Member]	Dec. 31, 2012 International [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2011 International [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2012 International [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2011 International [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2012 International [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2011 International [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2011 Global [Member]		Dec. 31, 2011 Global [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]		Dec. 31, 2011 Global [Member] Significant Observable Inputs, Level 2 [Member]		Dec. 31, 2011 Global [Member] Significant Unobservable Inputs, Level 3 [Member]		Dec. 31, 2012 Commodities [Member]		Dec. 31, 2011 Commodities [Member]		Dec. 31, 2012 Commodities [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]		Dec. 31, 2011 Commodities [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]		Dec. 31, 2012 Commodities [Member] Significant Observable Inputs, Level 2 [Member]		Dec. 31, 2011 Commodities [Member] Significant Observable Inputs, Level 2 [Member]		Dec. 31, 2012 Commodities [Member] Significant Unobservable Inputs, Level 3 [Member]		Dec. 31, 2011 Commodities [Member] Significant Unobservable Inputs, Level 3 [Member]		Dec. 31, 2012 Fixed Income [Member]	Dec. 31, 2011 Fixed Income [Member]	Dec. 31, 2012 Fixed Income [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2011 Fixed Income [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2012 Fixed Income [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2011 Fixed Income [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2012 Fixed Income [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2011 Fixed Income [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2012 Government Securities [Member]	Dec. 31, 2011 Government Securities [Member]	Dec. 31, 2012 Government Securities [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2011 Government Securities [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2012 Government Securities [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2011 Government Securities [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2012 Government Securities [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2011 Government Securities [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2012 Investment Grade Bonds [Member]	Dec. 31, 2011 Investment Grade Bonds [Member]	Dec. 31, 2012 Investment Grade Bonds [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2011 Investment Grade Bonds [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]	Dec. 31, 2012 Investment Grade Bonds [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2011 Investment Grade Bonds [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2012 Investment Grade Bonds [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2011 Investment Grade Bonds [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2012 High Yield [Member]		Dec. 31, 2011 High Yield [Member]		Dec. 31, 2012 High Yield [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]		Dec. 31, 2011 High Yield [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]		Dec. 31, 2012 High Yield [Member] Significant Observable Inputs, Level 2 [Member]		Dec. 31, 2011 High Yield [Member] Significant Observable Inputs, Level 2 [Member]		Dec. 31, 2012 High Yield [Member] Significant Unobservable Inputs, Level 3 [Member]		Dec. 31, 2011 High Yield [Member] Significant Unobservable Inputs, Level 3 [Member]		Dec. 31, 2012 Other Type of Invesments [Member]		Dec. 31, 2011 Other Type of Invesments [Member]		Dec. 31, 2012 Other Type of Invesments [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]		Dec. 31, 2011 Other Type of Invesments [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]		Dec. 31, 2012 Other Type of Invesments [Member] Significant Observable Inputs, Level 2 [Member]		Dec. 31, 2011 Other Type of Invesments [Member] Significant Observable Inputs, Level 2 [Member]		Dec. 31, 2012 Other Type of Invesments [Member] Significant Unobservable Inputs, Level 3 [Member]		Dec. 31, 2011 Other Type of Invesments [Member] Significant Unobservable Inputs, Level 3 [Member]		Dec. 31, 2012 Alternative Investments [Member]		Dec. 31, 2011 Alternative Investments [Member]		Dec. 31, 2012 Alternative Investments [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]		Dec. 31, 2011 Alternative Investments [Member] Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]		Dec. 31, 2012 Alternative Investments [Member] Significant Observable Inputs, Level 2 [Member]		Dec. 31, 2011 Alternative Investments [Member] Significant Observable Inputs, Level 2 [Member]		Dec. 31, 2012 Alternative Investments [Member] Significant Unobservable Inputs, Level 3 [Member]		Dec. 31, 2011 Alternative Investments [Member] Significant Unobservable Inputs, Level 3 [Member]		Dec. 31, 2012 Director [Member] Deferred Compensation Plan [Member]	Dec. 31, 2011 Director [Member] Deferred Compensation Plan [Member]	Dec. 31, 2010 Director [Member] Deferred Compensation Plan [Member]	Dec. 31, 2012 Pension Benefits [Member]	Dec. 31, 2011 Pension Benefits [Member]	Dec. 31, 2010 Pension Benefits [Member]	Dec. 31, 2012 Post-retirement Benefits [Member]	Dec. 31, 2011 Post-retirement Benefits [Member]	Dec. 31, 2010 Post-retirement Benefits [Member]	Dec. 31, 2012 Pentegra DB Plan [Member] Tupper Lake National Bank [Member]	Dec. 31, 2011 Pentegra DB Plan [Member] Tupper Lake National Bank [Member]	Dec. 31, 2010 Pentegra DB Plan [Member] Tupper Lake National Bank [Member]	Jun. 30, 2011 Pentegra DB Plan [Member] Tupper Lake National Bank [Member]	Jun. 30, 2010 Pentegra DB Plan [Member] Tupper Lake National Bank [Member]	Dec. 31, 2012 Unfunded Supplementary Pension Plans [Member]	Dec. 31, 2011 Unfunded Supplementary Pension Plans [Member]	Dec. 31, 2012 Unfunded Stock Balance [Member] Nonemployee Directors [Member]	Dec. 31, 2011 Unfunded Stock Balance [Member] Nonemployee Directors [Member]
Change in benefit obligation [Roll Forward]
Benefit obligation at the beginning of year																																																																																																																																																														$ 112,857,000	$ 81,321,000		$ 3,352,000	$ 3,594,000					$ 2,900,000,000		$ 12,000,000	$ 9,300,000	$ 200,000	$ 200,000
Service cost																																																																																																																																																														3,392,000	2,959,000	2,780,000	0	0	0
Interest cost																																																																																																																																																														4,393,000	4,497,000	3,909,000	114,000	153,000	195,000
Participant contributions																																																																																																																																																														0	0		502,000	706,000
Plan acquisitions/amendment																																																																																																																																																														0	17,511,000		0	0
Deferred actuarial loss (gain)																																																																																																																																																														9,352,000	11,713,000		(72,000)	46,000
Benefits paid																																																																																																																																																														(6,255,000)	(5,144,000)		(845,000)	(1,147,000)
Benefit obligation at end of year																																																																																																																																																														123,739,000	112,857,000	81,321,000	3,051,000	3,352,000	3,594,000				2,900,000,000		12,000,000	9,300,000	200,000	200,000
Change in plan assets [Roll Forward]
Fair value of plan assets at beginning of year	126,300,000										20,387,000	31,389,000	410,000	540,000	19,977,000	30,849,000	0	0	87,507,000	58,680,000	87,507,000	58,680,000	0	0	0	0	40,547,000	26,468,000	40,547,000	26,468,000	0	0	0	0	10,311,000	6,004,000	10,311,000	6,004,000	0	0	0	0	11,486,000	10,512,000	11,486,000	10,512,000	0	0	0	0	22,428,000	10,923,000	22,428,000	10,923,000	0	0	0	0	2,936,000	[1]	2,936,000	[1]	0	[1]	0	[1]	2,735,000	[2]	1,837,000	[2]	2,735,000	[2]	1,837,000	[2]	0	[2]	0	[2]	0	[2]	0	[2]	35,685,000	31,462,000	27,416,000	22,966,000	8,269,000	8,496,000	0	0	12,106,000	16,600,000	3,837,000	8,600,000	8,269,000	8,000,000	0	0	12,063,000	4,965,000	12,063,000	4,965,000	0	0	0	0	11,516,000	[3]	9,897,000	[3]	11,516,000	[3]	9,401,000	[3]	0	[3]	496,000	[3]	0	[3]	0	[3]	143,661,000	[4]	126,309,000	[4]	115,333,000	[4]	86,870,000	[4]	28,328,000	[4]	39,439,000	[4]	0	[4]	0	[4]	82,000	[5]	4,778,000	[5]	0	[5]	4,684,000	[5]	82,000	[5]	94,000	[5]	0	[5]	0	[5]				126,309,000	96,439,000		0	0						2,700,000,000
Actual return of plan assets																																																																																																																																																														10,992,000	1,479,000		0	0
Participant contributions																																																																																																																																																														0	0		502,000	706,000
Employer contributions																																																																																																																																																														12,615,000	11,623,000		343,000	441,000
Plan acquisition																																																																																																																																																														0	21,912,000		0	0
Benefits paid																																																																																																																																																														(6,255,000)	(5,144,000)		(845,000)	(1,147,000)
Fair value of plan assets at end of year	143,700,000	126,300,000									20,387,000	31,389,000	410,000	540,000	19,977,000	30,849,000	0	0	87,507,000	58,680,000	87,507,000	58,680,000	0	0	0	0	40,547,000	26,468,000	40,547,000	26,468,000	0	0	0	0	10,311,000	6,004,000	10,311,000	6,004,000	0	0	0	0	11,486,000	10,512,000	11,486,000	10,512,000	0	0	0	0	22,428,000	10,923,000	22,428,000	10,923,000	0	0	0	0	2,936,000	[1]	2,936,000	[1]	0	[1]	0	[1]	2,735,000	[2]	1,837,000	[2]	2,735,000	[2]	1,837,000	[2]	0	[2]	0	[2]	0	[2]	0	[2]	35,685,000	31,462,000	27,416,000	22,966,000	8,269,000	8,496,000	0	0	12,106,000	16,600,000	3,837,000	8,600,000	8,269,000	8,000,000	0	0	12,063,000	4,965,000	12,063,000	4,965,000	0	0	0	0	11,516,000	[3]	9,897,000	[3]	11,516,000	[3]	9,401,000	[3]	0	[3]	496,000	[3]	0	[3]	0	[3]	143,661,000	[4]	126,309,000	[4]	115,333,000	[4]	86,870,000	[4]	28,328,000	[4]	39,439,000	[4]	0	[4]	0	[4]	82,000	[5]	4,778,000	[5]	0	[5]	4,684,000	[5]	82,000	[5]	94,000	[5]	0	[5]	0	[5]				143,661,000	126,309,000	96,439,000	0	0	0					2,700,000,000
Defined Benefit Plan, Funded Status of Plan [Abstract]
Over/(Under) funded status at year end																																																																																																																																																														19,922,000	13,452,000		(3,051,000)	(3,352,000)
Amounts recognized in the consolidated balance sheet [Abstract]
Other assets																																																																																																																																																														32,135,000	22,929,000		0	0
Other liabilities																																																																																																																																																														(12,213,000)	(9,477,000)		(3,051,000)	(3,352,000)
Amounts recognized in accumulated other comprehensive income (AOCI) [Abstract]
Net (gain) loss																																																																																																																																																														47,988,000	44,119,000		288,000	371,000
Net prior service (credit) cost																																																																																																																																																														(526,000)	(674,000)		(2,517,000)	(3,339,000)
Pre-tax adjustment to AOCI																																																																																																																																																														47,462,000	43,445,000		(2,229,000)	(2,968,000)
Taxes																																																																																																																																																														(18,296,000)	(16,738,000)		848,000	1,135,000
Net adjustment to AOCI	27,785,000	24,874,000		14,292,000																																																																																																																																																										29,166,000	26,707,000		(1,381,000)	(1,833,000)
Benefit obligation for defined benefit pension plan prior to plan revaluation	111,500,000	103,400,000
Accumulated other comprehensive income (loss), negative postretirement medical plan amendment, arising during period, net of tax			3,500,000
Amounts recognized in AOCI, net of tax [Abstract]
Prior service cost																																																																																																																																																														90,000	92,000		503,000	650,000
Net (gain) loss																																																																																																																																																														2,368,000	9,816,000		(51,000)	24,000
Total																																																																																																																																																														2,458,000	9,908,000		452,000	674,000
Costs that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in net periodic (income) cost in next fiscal year [Abstract]
Prior service cost																																																																																																																																																														(51,000)			(179,000)
Net loss																																																																																																																																																														3,802,000			16,000
Total																																																																																																																																																														3,751,000			(163,000)
Weighed average assumption used in calculating benefit obligations [Abstract]
Discount rate (in hundredths)																																																																																																																																																														3.40%	4.10%		3.20%	3.90%
Expected return on plan assets (in hundredths)																																																																																																																																																														7.00%	7.50%
Rate of compensation increase (in hundredths)																																																																																																																																																														3.50%	4.00%
Net periodic benefit cost [Abstract]
Service cost																																																																																																																																																														3,392,000	2,959,000	2,780,000	0	0	0
Interest cost																																																																																																																																																														4,393,000	4,497,000	3,909,000	114,000	153,000	195,000
Expected return on plan assets																																																																																																																																																														(9,196,000)	(8,097,000)	(6,470,000)	0	0	0
Amortization of unrecognized net loss																																																																																																																																																														3,687,000	2,362,000	2,421,000	11,000	8,000	17,000
Amortization of prior service cost																																																																																																																																																														(147,000)	(149,000)	(189,000)	(822,000)	(1,057,000)	(1,057,000)
Net periodic benefit cost																																																																																																																																																														2,129,000	1,572,000	2,451,000	(697,000)	(896,000)	(845,000)
Prior service costs [Abstract]
Maximum percentage of net gain or loss over the greater of the projected benefit obligation or the market-related value of assets without requiring amortization (hundredths)	10.00%
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate (in hundredths)																																																																																																																																																														4.10%	4.40%	5.60%	3.90%	4.50%	5.15%
Expected return on plan assets (in hundredths)																																																																																																																																																														7.50%	7.50%	7.50%
Rate of compensation increase (in hundredths)																																																																																																																																																														4.00%	4.00%	4.00%
Estimated Future Benefit Payments [Abstract]
2013																																																																																																																																																														7,130,000			339,000
2014																																																																																																																																																														7,510,000			259,000
2015																																																																																																																																																														6,986,000			241,000
2016																																																																																																																																																														7,848,000			211,000
2017																																																																																																																																																														7,777,000			203,000
2018-2022																																																																																																																																																														44,898,000			881,000
Plan Assets [Abstract]
Target allocation percentage of assets, equity securities (in hundredths)	60.00%
Target allocation percentage of assets, debt securities (in hundredths)	40.00%
Maximum percentage of alternative investments authorized to be purchased (in hundredths)	15.00%
Maximum percentage of portfolio invested in company stock (in hundredths)	10.00%
Fair value of plan assets	143,700,000	126,300,000									20,387,000	31,389,000	410,000	540,000	19,977,000	30,849,000	0	0	87,507,000	58,680,000	87,507,000	58,680,000	0	0	0	0	40,547,000	26,468,000	40,547,000	26,468,000	0	0	0	0	10,311,000	6,004,000	10,311,000	6,004,000	0	0	0	0	11,486,000	10,512,000	11,486,000	10,512,000	0	0	0	0	22,428,000	10,923,000	22,428,000	10,923,000	0	0	0	0	2,936,000	[1]	2,936,000	[1]	0	[1]	0	[1]	2,735,000	[2]	1,837,000	[2]	2,735,000	[2]	1,837,000	[2]	0	[2]	0	[2]	0	[2]	0	[2]	35,685,000	31,462,000	27,416,000	22,966,000	8,269,000	8,496,000	0	0	12,106,000	16,600,000	3,837,000	8,600,000	8,269,000	8,000,000	0	0	12,063,000	4,965,000	12,063,000	4,965,000	0	0	0	0	11,516,000	[3]	9,897,000	[3]	11,516,000	[3]	9,401,000	[3]	0	[3]	496,000	[3]	0	[3]	0	[3]	143,661,000	[4]	126,309,000	[4]	115,333,000	[4]	86,870,000	[4]	28,328,000	[4]	39,439,000	[4]	0	[4]	0	[4]	82,000	[5]	4,778,000	[5]	0	[5]	4,684,000	[5]	82,000	[5]	94,000	[5]	0	[5]	0	[5]				143,661,000	126,309,000	96,439,000	0	0	0					2,700,000,000
Percentage of global equity securities invested in U.S. equity securities (in hundredths)	50.00%
Percentage of global equity securities invested in international equity securities (in hundredths)	50.00%
Total dividends and interest receivable excluded from plan assets	223,000	306,000
Projected benefit obligation																																																																																																																																																														123,739,000	112,857,000	81,321,000	3,051,000	3,352,000	3,594,000				2,900,000,000		12,000,000	9,300,000	200,000	200,000
Defined Benefit Plan, Minimum Percentage Plan Funded (in hundredths)																																																																																																																																																																								80.00%
Multi-employer plan, contributions																																																																																																																																																																				53,000	131,000	39,000
Assumed Health Care Cost Trend Rates [Abstract]
Assumed health care cost trend rate for participants younger than 65 (in hundredths)	8.00%
Assumed health care cost trend rate for participants older than 65 (in hundredths)	6.00%
Assumed health care cost trend rate for prescription drugs (in hundredths)	6.50%
Ultimate health care cost trend rate (in hundredths)	5.00%
Year that rate reaches ultimate trend rate	2021
Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract]
Effect of one percentage point increase on service and interest cost components	300
Effect of one percentage point increase on benefit obligation	7,000
Effect of One percentage point decrease on service and interest cost components	300
Effect of One percentage point decrease on benefit obligation	8,000
401(k) Employee Stock Ownership Plan [Abstract]
Contribution from eligible compensation, minimum (in hundredths)								1.00%
Contribution from eligible compensation, maximum (in hundredths)								90.00%
Percentage of first eligible compensation fully matched by employer (in hundredths)								3.00%
Percentage of matching contribution in the form of common stock (in hundredths)								100.00%
Percentage of the next eligible compensation matched at 50% by employer (in hundredths)								3.00%
Percentage of matching contributions for the next eligible compensation in the form of company stock (in hundredths)								50.00%
Expense recognized under plan					439,000	584,000	546,000	2,956,000	2,752,000	2,536,000																																																																																																																																																	148,000	125,000	107,000
Liability recorded for compensation plan					4,729,000	4,734,000																																																																																																																																																					3,117,000	2,863,000
Interest credit contribution expense recognized for 401(k) plan								$ 419,000	$ 203,000
Deferred Compensation Arrangement with Individual, Shares credited																																																																																																																																																											146,298	140,029

[1] This category includes securities that invest approximately 50% in U.S. equity securities and 50% international equity securities.

[2] This category includes investments in exchange traded funds reflecting the performance of an underlying commodity index.

[3] This category is exchange-traded funds representing a diversified index of high yield corporate bonds.

[4] Excludes dividends and interest receivable totaling $223,000 and $306,000 at December 31, 2012 and 2011, respectively.

[5] This category is comprised of non-traditional investment classes including private equity funds and alternative exchange funds.