Statements of Common Stockholders' Equity (Unaudited) (USD $) In Thousands, except Share data	Common Stock [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2010	$ 75,481	$ 15,776	$ 91,257
Balance (in shares) at Dec. 31, 2010	12,692,054
Net income	0	6,961	6,961
Dividends	0	(5,001)	(5,001)
Issuance of common stock under dividend reinvestment, direct stock and employee stock purchase plans	1,232	0	1,232
Issuance of common stock under dividend reinvestment, direct stock and employee stock purchase plans (in shares)	75,729
Balance at Sep. 30, 2011	76,713	17,736	94,449
Balance (in shares) at Sep. 30, 2011	12,767,783
Balance at Dec. 31, 2011	77,113	18,152	95,265
Balance (in shares) at Dec. 31, 2011	12,791,671		12,791,671
Net income	0	6,905	6,905
Dividends	0	(5,145)	(5,145)
Issuance of common stock under dividend reinvestment, direct stock and employee stock purchase plans	1,634	0	1,634
Issuance of common stock under dividend reinvestment, direct stock and employee stock purchase plans (in shares)	94,611
Balance at Sep. 30, 2012	$ 78,747	$ 19,912	$ 98,659
Balance (in shares) at Sep. 30, 2012	12,886,282		12,886,282