Consolidated Statements of Income (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Interest and dividend income:
Interest and fees on loans	$ 34,421	$ 32,166	$ 100,909	$ 95,286
Interest and dividends on securities available for sale:
U. S. government sponsored enterprises	297	571	1,184	2,014
State and political subdivisions	38	127	150	466
Mortgage-backed securities and collateralized mortgage obligations-residential	3,040	2,888	9,417	8,358
Corporate bonds	2	223	63	674
Small Business Administration-guaranteed participation securities	535	558	1,630	1,618
Mortgage-backed securities and collateralized mortgage obligations-commercial	38	39	114	106
Interest and Dividend Income, Other Available for Sale Securities	4	5	12	13
Total interest and dividends on securities available for sale	3,954	4,411	12,570	13,249
Interest on held to maturity securities:
Mortgage-backed securities and collateralized mortgage obligations-residential	545	686	1,747	2,191
Corporate bonds	153	154	461	680
Total interest on held to maturity securities	698	840	2,208	2,871
Federal Reserve Bank and Federal Home Loan Bank stock	127	121	388	361
Interest on federal funds sold and other short-term investments	374	344	1,101	916
Total interest income	39,574	37,882	117,176	112,683
Interest on deposits [Abstract]
Interest-bearing checking	94	84	267	246
Savings	644	798	1,999	2,543
Money market deposit accounts	648	590	1,865	1,905
Time deposits	2,213	1,937	6,199	5,640
Interest on short-term borrowings	327	370	1,062	1,101
Total interest expense	3,926	3,779	11,392	11,435
Net interest income	35,648	34,103	105,784	101,248
Provision for loan losses	1,100	1,500	4,100	5,500
Net interest income after provision for loan losses	34,548	32,603	101,684	95,748
Noninterest income:
Trustco financial services income	1,471	1,317	4,386	4,025
Fees for services to customers	2,838	2,903	8,091	8,758
Net gain on securities transactions	376	0	382	1,434
Other	205	194	2,295	705
Total noninterest income	4,890	4,414	15,154	14,922
Noninterest expenses:
Salaries and employee benefits	8,272	7,935	23,876	23,760
Net occupancy expense	4,013	3,911	12,382	11,874
Equipment expense	1,725	1,567	5,300	4,867
Professional services	1,547	1,255	4,271	4,240
Outsourced services	1,375	1,350	4,125	4,050
Advertising expense	629	548	1,885	1,992
FDIC and other insurance	1,054	1,009	2,958	3,023
Other real estate expense, net	1,001	946	168	3,168
Other	2,576	2,167	7,465	7,140
Total noninterest expenses	22,192	20,688	62,430	64,114
Income before taxes	17,246	16,329	54,408	46,556
Income taxes	6,532	6,077	20,875	17,373
Net income	$ 10,714	$ 10,252	$ 33,533	$ 29,183
Net income per Common Share:
Basic (in dollars per share)	$ 0.113	$ 0.109	$ 0.354	$ 0.310
Diluted (in dollars per share)	$ 0.113	$ 0.109	$ 0.354	$ 0.310