Statements of Common Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	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	4,868	4,868
Dividends	0	(3,694)	(3,694)
Retirement of common stock	$ (4,755)	0	$ (4,755)
Retirement of common stock (in shares)	(235,420)		(235,420)
Issuance of common stock under dividend reinvestment, direct stock and employee stock purchase plans	$ 1,662	0	$ 1,662
Issuance of common stock under dividend reinvestment, direct stock and employee stock purchase plans (in shares)	83,506
Balance at Jun. 30, 2014	$ 77,452	24,140	101,592
Balance (in shares) at Jun. 30, 2014	12,827,367
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	5,453	$ 5,453
Dividends	0	(3,843)	$ (3,843)
Retirement of common stock (in shares)			0
Issuance of common stock under dividend reinvestment, direct stock and employee stock purchase plans	$ 1,157	0	$ 1,157
Issuance of common stock under dividend reinvestment, direct stock and employee stock purchase plans (in shares)	51,573
Balance at Jun. 30, 2015	$ 78,713	$ 28,617	$ 107,330
Balance (in shares) at Jun. 30, 2015	12,882,094		12,882,094