Statements of Common Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2014	$ 77,556	$ 27,007	$ 104,563
Balance (in shares) at Dec. 31, 2014	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
Balance at Dec. 31, 2015	$ 77,317	31,753	$ 109,070
Balance (in shares) at Dec. 31, 2015	12,812,377		12,812,377
Net income	$ 0	2,486	$ 2,486
Dividends	0	(1,995)	$ (1,995)
Retirement of common stock (in shares)			0
Issuance of common stock under dividend reinvestment, direct stock and employee stock purchase plans	$ 733	0	$ 733
Issuance of common stock under dividend reinvestment, direct stock and employee stock purchase plans (in shares)	27,358
Balance at Mar. 31, 2016	$ 78,050	$ 32,244	$ 110,294
Balance (in shares) at Mar. 31, 2016	12,839,735		12,839,735