PARENT COMPANY FINANCIAL INFORMATION (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets:
Cash on deposit with subsidiary bank	$ 33,040	$ 27,966
Securities available for sale, at estimated fair value	242,258	293,091
Total assets	1,755,343	1,707,620	$ 1,657,179
Liabilities and shareholders' equity:
Dividends payable	1,254	1,233	1,225
Total liabilities	1,590,314	1,557,807
Shareholders' equity:
Total shareholders' equity	165,029	149,813	143,748	$ 137,242
Total liabilities and shareholders' equity	1,755,343	1,707,620
STATEMENTS OF INCOME [Abstract]
Income before income tax expense	23,635	14,692	14,431
Income tax benefit	4,009	7,262	4,404
Net of tax	19,626	7,430	10,027
Cash flows from operating activities:
Net income	19,626	7,430	10,027
Adjustments to reconcile net income to net cash provided by operating activities:
Change in other assets	(2,651)	579	(198)
Change in other liabilities	(654)	(3,664)	5,427
Net cash provided by operating activities	27,772	23,645	22,141
Cash flow from financing activities:
Cash dividends paid	(4,969)	(4,917)	(4,878)
Sale of treasury stock	643	582	438
Net cash provided by financing activities	27,552	39,564	26,565
Net increase (decrease) in cash and cash equivalents	99,243	(43,433)	47,977
Cash and cash equivalents, beginning of period	30,729	74,162	26,185
Cash and cash equivalents, end of period	129,972	30,729	74,162
Parent Company
Assets:
Cash on deposit with subsidiary bank	3,978	3,017
Dividends receivable from subsidiary bank	0	1,233
Securities available for sale, at estimated fair value	554	420
Other assets	1,071	1,039
Total assets	166,390	151,121
Liabilities and shareholders' equity:
Dividends payable	1,254	1,233
Other liabilities	107	75
Total liabilities	1,361	1,308
Shareholders' equity:
Total shareholders' equity	165,029	149,813
Total liabilities and shareholders' equity	166,390	151,121
STATEMENTS OF INCOME [Abstract]
Dividends from subsidiary bank and non-bank	3,187	4,926	4,889
Interest and dividend income	10	10	9
Non-interest income	(20)	22	0
Non-interest expenses	477	433	526
Income before income tax expense	2,700	4,525	4,372
Income before income tax expense	19,462	7,213	9,763
Income tax benefit	(164)	(217)	(264)
Net of tax	19,626	7,430	10,027
Cash flows from operating activities:
Net income	19,626	7,430	10,027
Adjustments to reconcile net income to net cash provided by operating activities:
Change in dividend receivable	1,233	(8)	(11)
Change in other assets	(32)	(214)	82
Change in other liabilities	773	51	(203)
Expense related to employee stock compensation	89	200	210
Expense related to restricted stock units for directors' deferred compensation plan	67	98	97
Expense to employee restricted stock awards	405	210	192
Net cash provided by operating activities	5,399	5,079	5,003
Cash flow from financing activities:
Cash dividends paid	(4,969)	(4,919)	(4,878)
Purchase of treasury stock	(112)	(61)	(22)
Sale of treasury stock	643	582	438
Net cash provided by financing activities	(4,438)	(4,398)	(4,462)
Net increase (decrease) in cash and cash equivalents	961	681	541
Cash and cash equivalents, beginning of period	3,017	2,336	1,795
Cash and cash equivalents, end of period	3,978	3,017	2,336
Parent Company | Chemung Canal Trust Company
Assets:
Investment in subsidiary	158,166	142,884
STATEMENTS OF INCOME [Abstract]
Income (loss) from equity method investments	16,670	1,939	4,856
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed earnings	(16,670)	(1,939)	(4,856)
Parent Company | CFS Group Inc.
Assets:
Investment in subsidiary	873	904
STATEMENTS OF INCOME [Abstract]
Income (loss) from equity method investments	(32)	(42)	(48)
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed earnings	32	42	48
Parent Company | Chemung Risk Management
Assets:
Investment in subsidiary	1,748	1,624
STATEMENTS OF INCOME [Abstract]
Income (loss) from equity method investments	124	791	583
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed earnings	$ (124)	$ (791)	$ (583)