Retirement Benefit Plans Retirement Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2013

Compensation and Retirement Disclosure [Abstract]

Schedule of Defined Benefit Plans Disclosures [Table Text Block]

The following tables set forth changes in the plans’ benefit obligations (projected benefit obligation for pension benefits and accumulated benefit obligation for postretirement benefits) and changes in the plans’ assets and the funded status of the pension plans and other postretirement benefit plan at December 31:

Schedule of Defined Benefit Plan Disclosures
	Employees' Pension Plan			Select Executive Retirement Plan			Postretirement Benefit Plans
Defined Benefit Plan Funded Status
December 31, 2013
Fair Value of Plan Assets	$	44,653		$	—		$	—
Benefit Obligation	33,259			4,459			7,619
Funded Status of Plan	$	11,394		$	(4,459	)	$	(7,619	)
December 31, 2012
Fair Value of Plan Assets	$	39,880		$	—		$	—
Benefit Obligation	37,046			5,324			9,213
Funded Status of Plan	$	2,834		$	(5,324	)	$	(9,213	)
Change in Benefit Obligation
Benefit Obligation, at January 1, 2013	$	37,046		$	5,324		$	9,213
Service Cost	1,506			—			211
Interest Cost	1,261			163			308
Plan Participants' Contributions	—			—			368
Amendments	—			—			—
Actuarial Gain	(3,820		)	(555		)	(1,648		)
Benefits Paid	(2,734		)	(473		)	(833		)
Benefit Obligation, at December 31, 2013	$	33,259		$	4,459		$	7,619

Schedule of Defined Benefit Plan Disclosures
	Employees' Pension Plan			Select Executive Retirement Plan			Postretirement Benefit Plans
Benefit Obligation, at January 1, 2012	$	35,047		$	4,529		$	8,556
Service Cost	1,467			87			202
Interest Cost	1,436			190			338
Plan Participants' Contributions	—			—			348
Amendments	—			405			—
Actuarial Loss	2,857			441			491
Benefits Paid	(3,761		)	(328		)	(722		)
Benefit Obligation, at December 31, 2012	$	37,046		$	5,324		$	9,213
Change in Fair Value of Plan Assets
Fair Value of Plan Assets, at January 1, 2013	$	39,880		$	—		$	—
Actual Return on Plan Assets	7,507			—			—
Employer Contributions	—			473			465
Plan Participants' Contributions	—			—			368
Benefits Paid	(2,734		)	(473		)	(833		)
Fair Value of Plan Assets, at December 31, 2013	$	44,653		$	—		$	—
Change in Fair Value of Plan Assets, continued
Fair Value of Plan Assets, at January 1, 2012	$	39,206		$	—		$	—
Actual Return on Plan Assets	4,435			—			—
Employer Contributions	—			328			374
Plan Participants' Contributions	—			—			348
Benefits Paid	(3,761		)	(328		)	(722		)
Fair Value of Plan Assets, at December 31, 2012	$	39,880		$	—		$	—
Accumulated Benefit Obligation at December 31, 2013	$	32,886		$	4,459		$	7,619
Amounts Recognized in the Consolidated Balance Sheets
December 31, 2013
Prepaid Pension Asset	$	11,394		$	—		—
Accrued Benefit Liability	—			(4,459		)	(7,619		)
Net Benefit Recognized	$	11,394		$	(4,459	)	$	(7,619	)
December 31, 2012
Prepaid Pension Asset	$	2,834		$	—		—
Accrued Benefit Liability	—			(5,324		)	(9,213		)
Net Benefit Recognized	$	2,834		$	(5,324	)	$	(9,213	)
Amounts Recognized in Other Comprehensive Income (Loss)
For the Year Ended December 31, 2013
Net Unamortized Gain Arising During the Period	$	(8,438	)	$	(554	)	$	(1,648	)
Net Prior Service Cost Arising During the Period	—			—			—
Amortization of Net Loss	(1,231		)	(140		)	(142		)
Amortization of Prior Service (Cost) Credit	(37		)	(79		)	114
Total Other Comprehensive (Loss) Income for Pension and      Other Postretirement Benefit Plans	$	(9,706	)	$	(773	)	$	(1,676	)
For the Year Ended December 31, 2012
Net Unamortized Loss Arising During the Period	$	1,286		$	441		$	491
Net Prior Service Cost Arising During the Period	—			405			—
Amortization of Net Loss	(1,387		)	(156		)	(134		)
Amortization of Prior Service (Cost) Credit	(41		)	(53		)	114
Total Other Comprehensive (Loss) Income for Pension and      Other Postretirement Benefit Plans	$	(142	)	$	637		$	471

Schedule of Defined Benefit Plan Disclosures
	Employees' Pension Plan			Select Executive Retirement Plan			Postretirement Benefit Plans
For the Year Ended December 31, 2011
Net Unamortized Loss Arising During the Period	$	5,474		$	151		$	504
Net Prior Service Cost Arising During the Period	191			75			—
Amortization of Net Loss	(778		)	(147		)	(71		)
Amortization of Prior Service (Cost) Credit	(38		)	32			114
Total Other Comprehensive (Loss) Income for Pension and      Other Postretirement Benefit Plans	$	4,849		$	111		$	547
Accumulated Other Comprehensive Income
December 31, 2013
Net Actuarial Loss	$	8,357		$	1,674		$	1,060
Prior Service (Credit) Cost	(255		)	642			(305		)
Total Accumulated Other Comprehensive Income, Before Tax	$	8,102		$	2,316		$	755
December 31, 2012
Net Actuarial Loss	$	18,026		$	2,368		$	2,850
Prior Service (Credit) Cost	(218		)	721			(419		)
Total Accumulated Other Comprehensive Income, Before Tax	$	17,808		$	3,089		$	2,431
Amounts that will be Amortized from Accumulated   Other Comprehensive Income the Next Year
Net Actuarial Loss	$	345		$	90		$	26
Prior Service (Credit) Cost	$	(45	)	$	72		$	(114	)
Net Periodic Benefit Cost
For the Year Ended December 31, 2013
Service Cost	$	1,506		$	—		$	211
Interest Cost	1,261			163			308
Expected Return on Plan Assets	(2,889		)	—			—
Amortization of Prior Service (Credit) Cost	37			79			(114		)
Amortization of Net Loss	1,232			139			142
Net Periodic Benefit Cost	$	1,147		$	381		$	547
For the Year Ended December 31, 2012
Service Cost	$	1,467		$	87		$	202
Interest Cost	1,436			190			338
Expected Return on Plan Assets	(2,865		)	—			—
Amortization of Prior Service (Credit) Cost	41			53			(114		)
Amortization of Net Loss	1,387			156			134
Net Periodic Benefit Cost	$	1,466		$	486		$	560
For the Year Ended December 31, 2011
Service Cost	$	1,353		$	81		$	173
Interest Cost	1,598			222			372
Expected Return on Plan Assets	(2,793		)	—			—
Amortization of Prior Service (Credit) Cost	38			(32		)	(114		)
Amortization of Net Loss	778			147			71
Net Periodic Benefit Cost	$	974		$	418		$	502
Weighted-Average Assumptions Used in   Calculating Benefit Obligation
December 31, 2013
Discount Rate	5.10		%	4.85		%	5.10		%
Rate of Compensation Increase	3.50		%	3.50		%	3.50		%

Schedule of Defined Benefit Plan Disclosures
	Employees' Pension Plan		Select Executive Retirement Plan		Postretirement Benefit Plans
Interest Rate Credit for Determining   Projected Cash Balance Account	4.00	%
Interest Rate to Annuitize Cash       Balance Account	5.25	%
Interest Rate to Convert Annuities To Actuarially   Equivalent Lump Sum Amounts	5.25	%	5.25	%
December 31, 2012
Discount Rate	3.55	%	3.15	%	3.55	%
Rate of Compensation Increase	3.50	%	3.50	%	3.50	%
Interest Rate Credit for Determining   Projected Cash Balance Account	3.00	%
Interest Rate to Annuitize Cash       Balance Account	4.50	%
Interest Rate to Convert Annuities To Actuarially   Equivalent Lump Sum Amounts	4.50	%	4.50	%
Weighted-Average Assumptions Used in   Calculating Net Periodic Benefit Cost
December 31, 2013
Discount Rate	3.55	%	3.15	%	3.55	%
Expected Long-Term Return on Plan Assets	7.50	%
Rate of Compensation Increase	3.50	%	3.50	%	3.50	%
Interest Rate Credit for Determining       Projected Cash Balance Account	3.00	%
Interest Rate to Annuitize Cash       Balance Account	4.50	%
Interest Rate to Convert AnnuitiesTo Actuarially   Equivalent Lump Sum Amounts	4.50	%	4.50	%
December 31, 2012
Discount Rate	4.05	%	4.05	%	4.05	%
Expected Long-Term Return on Plan Assets	7.50	%
Rate of Compensation Increase	3.50	%	3.50	%	3.50	%
Interest Rate Credit for Determining       Projected Cash Balance Account	3.25	%
Interest Rate to Annuitize Cash       Balance Account	5.00	%
Interest Rate to Convert AnnuitiesTo Actuarially   Equivalent Lump Sum Amounts	5.00	%	5.00	%
December 31, 2011
Discount Rate	5.15	%	5.15	%	5.15	%
Expected Long-Term Return on Plan Assets	7.50	%
Rate of Compensation Increase	3.50	%	3.50	%	3.50	%
Interest Rate Credit for Determining       Projected Cash Balance Account	4.25	%
Interest Rate to Annuitize Cash       Balance Account	5.50	%
Interest Rate to Convert AnnuitiesTo Actuarially   Equivalent Lump Sum Amounts	5.50	%	5.50	%

Schedule of Defined Benefit Plan Disclosures Information about Defined Benefit Plan Assets - Employees' Pension Plan
	Fair Value Measurements Using:
Asset Category	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total		Percent of Total		Target Allocation Minimum		Target Allocation Maximum
December 31, 2013
Cash	$	7	$	—	$	—	$	7	—	%	—	%	15.0	%
Interest-Bearing Money Market Fund	3,941		—		—		3,941		8.8	%	—	%	15.0	%
Arrow Common Stock1	4,291		—		—		4,291		9.6	%	—	%	10.0	%
North Country Funds - Equity 2	17,419		—		—		17,419		39.1	%
Other Mutual Funds - Equity	14,338		—		—		14,338		32.1	%
Total Equity Funds	31,757		—		—		31,757		71.2	%	55.0	%	85.0	%
North Country Funds - Fixed income 2	4,309		—		—		4,309		9.6	%
Other Mutual Funds - Fixed Income	348		—		—		348		0.8	%
Total Fixed Income Funds	4,657		—		—		4,657		10.4	%	10.0	%	30.0	%
Total	$	44,653	$	—	$	—	$	44,653	100.0	%
December 31, 2012
Cash	$	17	$	—	$	—	$	17	—	%	—	%	15.0	%
Interest-Bearing Money Market Fund	5,236		—		—		5,236		13.1	%	—	%	15.0	%
Arrow Common Stock	4,197		—		—		4,197		10.5	%	—	%	10.0	%
North Country Funds - Equity 2	13,043		—		—		13,043		32.8	%
Other Mutual Funds - Equity	11,160		—		—		11,160		28.0	%
Total Equity Funds	24,203		—		—		24,203		60.8	%	55.0	%	85.0	%
North Country Funds - Fixed income 2	4,236		—		—		4,236		10.6	%
Other Mutual Funds - Fixed Income	1,991		—		—		1,991		5.0	%
Total Fixed Income Funds	6,227		—		—		6,227		15.6	%	10.0	%	30.0	%
Total	$	39,880	$	—	$	—	$	39,880	100.0	%

¹ Acquisition of Arrow Financial Corporation common stock was under 10% of the total fair value of the employee's pension plan assets at the time of acquisition.

² The North Country Funds - Equity and the North Country Funds - Fixed Income are publicly traded mutual funds advised by Arrow's subsidiary, North Country Investment Advisers, Inc.

Schedule of Defined Benefit Plan Disclosures
	Employees' Pension Plan		Select Executive Retirement Plan		Postretirement Benefit Plans
Expected Future Benefit Payments
2014	$	3,068	$	452	$	510
2015	2,047		440		531
2016	2,344		416		539
2017	2,252		402		549
2018	2,165		388		562
2019-2023	12,516		1,699		3,026
Estimated Contributions During 2014	$	—	$	452	$	510
Assumed Health Care Cost Trend Rates
December 31, 2013
Health Care Cost Trend   Rate Assumed for Next Year					8.50		%
Rate to which the Cost Trend   Rate is Assumed to Decline   (the Ultimate Trend Rate)					5.00		%
Year that the Rate Reaches    the Ultimate Trend Rate					2021
December 31, 2012
Health Care Cost Trend   Rate Assumed for Next Year					9.00		%
Rate to which the Cost Trend   Rate is Assumed to Decline   (the Ultimate Trend Rate)					5.00		%
Year that the Rate Reaches    the Ultimate Trend Rate					2021
Effect of a One-Percentage Point Change in Assumed   Health Care Cost Trend Rates
Effect of a One Percentage Point Increase on   Service and Interest Cost Components					$	59
Effect of a One Percentage Point Decrease on   Service and Interest Cost Components					(49		)
Effect of a One Percentage Point Increase on   Accumulated Postretirement Benefit Obligation					557
Effect of a One Percentage Point Decrease on   Accumulated Postretirement Benefit Obligation					(478		)