BENEFIT PLANS, Fair Value of Plan Assets by Assets Category (Details) - USD ($) $ in Thousands		2 Months Ended	12 Months Ended
		Mar. 01, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]		$ 180,086	$ 171,625
Total dividends and interest receivable excluded from plan assets			300	400
Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]		166,117	159,324
Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]		13,969	12,301
Significant Unobservable Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]		0	0
Money Market Accounts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			8,151	7,990
Money Market Accounts [Member] | Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			103	2,240
Money Market Accounts [Member] | Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			8,048	5,750
Money Market Accounts [Member] | Significant Unobservable Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	0
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			96,748	83,868
Equity Securities [Member] | Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			96,748	83,868
Equity Securities [Member] | Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	0
Equity Securities [Member] | Significant Unobservable Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	0
U.S. Large-Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			43,235	34,985
U.S. Large-Cap [Member] | Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			43,235	34,985
U.S. Large-Cap [Member] | Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	0
U.S. Large-Cap [Member] | Significant Unobservable Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	0
U.S Mid/Small Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			19,032	12,354
U.S Mid/Small Cap [Member] | Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			19,032	12,354
U.S Mid/Small Cap [Member] | Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	0
U.S Mid/Small Cap [Member] | Significant Unobservable Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	0
CBSI Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			7,417	8,393
CBSI Stock [Member] | Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			7,417	8,393
CBSI Stock [Member] | Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	0
CBSI Stock [Member] | Significant Unobservable Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	0
International [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			27,064	28,136
International [Member] | Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			27,064	28,136
International [Member] | Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	0
International [Member] | Significant Unobservable Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	0
Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			63,106	69,767
Fixed Income Securities [Member] | Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			57,243	63,279
Fixed Income Securities [Member] | Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			5,863	6,488
Fixed Income Securities [Member] | Significant Unobservable Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	0
Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			31,238	37,885
Government Securities [Member] | Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			25,375	31,397
Government Securities [Member] | Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			5,863	6,488
Government Securities [Member] | Significant Unobservable Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	0
Investment Grade Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			15,253	14,517
Investment Grade Bonds [Member] | Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			15,253	14,517
Investment Grade Bonds [Member] | Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	0
Investment Grade Bonds [Member] | Significant Unobservable Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	0
International Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets				5,085
International Bonds [Member] | Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets				5,085
International Bonds [Member] | Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets				0
International Bonds [Member] | Significant Unobservable Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets				0
High Yield [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]		16,615	17,365
High Yield [Member] | Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]		16,615	17,365
High Yield [Member] | Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]		0	0
High Yield [Member] | Significant Unobservable Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]		0	0
Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]		12,081	10,000
Other Investments [Member] | Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]		12,023	9,937
Other Investments [Member] | Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]		58	63
Other Investments [Member] | Significant Unobservable Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]		0	0
State Bank of Chittenango Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions			0
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			180,400	172,026	$ 177,865
Employer contributions			$ 2,146	$ 616
Subsequent Event [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		$ 2,900

[1] Excludes dividends and interest receivable totaling $0.3 million and $0.4 million at December 31, 2016 and 2015, respectively.

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

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