Stock and Other Incentive Plans (Details 1) (Employee Stock Purchase Plan [Member], USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Employee Stock Purchase Plan [Member]
Stock Options Outstanding (in shares):
Outstanding, beginning of year	425,196	392,517	335,608
Granted	327,936	261,960	256,080
Exercised	(59,163)	(13,901)	(9,131)
Forfeited	(78,202)	(49,173)	(53,504)
Expired	(182,315)	(166,207)	(136,536)
Outstanding, end of period	433,452	425,196	392,517
Exerciseable, end of year	433,452	425,196	392,517
Weighted-average exercise price of (in dollars per share):
Options outstanding, beginning of year	$ 15.80	$ 17.99	$ 18.24
Options granted during the year	$ 15.80	$ 17.99	$ 18.24
Options exercised during the year	$ 16.18	$ 16.31	$ 18.19
Options forfeited during the year	$ 16.74	$ 17.12	$ 18.69
Options expired during the year	$ 18.24	$ 19.34	$ 19.80
Options outstanding, end of year	$ 16.78	$ 15.80	$ 17.99
Weighted-average fair value of options granted during the year (calculated as of the grant date)	$ 4.13	$ 7.61	$ 8.07
Intrinsic value of options exercised during the year	$ 439,645	$ 38,784	$ 29,037
Intrinsic value of options outstanding (calculated as of December 31)	3,132,506	1,186,297	1,248,204
Intrinsic value of options exercisable (calculated as of December 31)	$ 3,132,506	$ 1,186,297	$ 1,248,204
Exercise prices of options outstanding (calculated as of December 31)	$ 16.78	$ 15.80	$ 17.99
Weighted-average contractual life of outstanding options (calculated as of December 31, in years)	9 months 18 days	9 months 18 days	9 months 18 days