Consolidated Statements of Income (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Interest and dividend income:
Interest and fees on loans	$ 31,481	$ 32,425
Interest and dividends on securities available for sale:
Total interest and dividends on securities available for sale	4,524	4,634
Interest on held to maturity securities:
Total interest on held to maturity securities	1,101	1,824
Federal Reserve Bank and Federal Home Loan Bank stock	119	90
Interest on federal funds sold and other short-term investments	245	320
Total interest income	37,470	39,293
Interest expense:
Interest-bearing checking	80	78
Savings	916	1,102
Money market deposit accounts	685	923
Time deposits	1,820	3,418
Interest on short-term borrowings	364	388
Total interest expense	3,865	5,909
Net interest income	33,605	33,384
Provision for loan losses	2,000	3,100
Net interest income after provision for loan losses	31,605	30,284
Noninterest income:
Trustco financial services income	1,421	1,394
Fees for services to customers	2,887	2,732
Net gain on securities transactions	2	677
Other	282	207
Total noninterest income	4,592	5,010
Noninterest expenses:
Salaries and employee benefits	8,178	7,743
Net occupancy expense	4,053	3,795
Equipment expense	1,718	1,520
Professional services	1,420	1,436
Outsourced services	1,350	1,250
Advertising expense	730	809
FDIC and other insurance	1,010	880
Other real estate expense, net	749	966
Other	2,349	2,737
Total noninterest expenses	21,557	21,136
Income before taxes	14,640	14,158
Income taxes	5,472	5,249
Net income	9,168	8,909
Net income per Common Share:
Basic (in dollars per share)	$ 0.097	$ 0.095
Diluted (in dollars per share)	$ 0.097	$ 0.095
U. S. government sponsored enterprises [Member]
Interest and dividends on securities available for sale:
Total interest and dividends on securities available for sale	816	2,304
Interest on held to maturity securities:
Total interest on held to maturity securities	0	25
State and political subdivisions [Member]
Interest and dividends on securities available for sale:
Total interest and dividends on securities available for sale	191	410
Mortgage-backed securities and collateralized mortgage obligations-residential [Member]
Interest and dividends on securities available for sale:
Total interest and dividends on securities available for sale	2,769	1,093
Interest on held to maturity securities:
Total interest on held to maturity securities	789	1,290
Corporate bonds [Member]
Interest and dividends on securities available for sale:
Total interest and dividends on securities available for sale	218	822
Interest on held to maturity securities:
Total interest on held to maturity securities	312	509
Small Business Administration-guaranteed participation securities [Member]
Interest and dividends on securities available for sale:
Total interest and dividends on securities available for sale	496	0
Mortgage-backed securities and collateralized mortgage obligations-Commercial [Member]
Interest and dividends on securities available for sale:
Total interest and dividends on securities available for sale	29	0
Other securities [Member]
Interest and dividends on securities available for sale:
Total interest and dividends on securities available for sale	$ 5	$ 5