Statements of Common Stockholders' Equity (Unaudited) (USD $) In Thousands, except Share data	Common Stock [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2013	$ 80,545	$ 22,966	$ 103,511
Balance (in shares) at Dec. 31, 2013	12,979,281
Net income	0	2,111	2,111
Dividends	0	(1,860)	(1,860)
Retirement of common stock	(572)	0	(572)
Retirement of common stock (in shares)	(27,980)		(27,980)
Issuance of common stock under dividend reinvestment, direct stock and employee stock purchase plans	782	0	782
Issuance of common stock under dividend reinvestment, direct stock and employee stock purchase plans (in shares)	38,890
Balance at Mar. 31, 2014	80,755	23,217	103,972
Balance (in shares) at Mar. 31, 2014	12,990,191
Balance at Dec. 31, 2014	77,556	27,007	104,563
Balance (in shares) at Dec. 31, 2014	12,830,521		12,830,521
Net income	0	2,528	2,528
Dividends	0	(1,919)	(1,919)
Retirement of common stock (in shares)			0
Issuance of common stock under dividend reinvestment, direct stock and employee stock purchase plans	577	0	577
Issuance of common stock under dividend reinvestment, direct stock and employee stock purchase plans (in shares)	25,183
Balance at Mar. 31, 2015	$ 78,133	$ 27,616	$ 105,749
Balance (in shares) at Mar. 31, 2015	12,855,704		12,855,704