Statements of Common Stockholders' Equity (Unaudited) (USD $) In Thousands, except Share data	Common Stock [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2012	$ 79,299	$ 20,526	$ 99,825
Balance (in shares) at Dec. 31, 2012	12,918,633
Net income	0	4,481	4,481
Dividends	0	(3,572)	(3,572)
Retirement of common stock	(1,746)	0	(1,746)
Retirement of common stock (in shares)	(93,052)		(93,052)
Issuance of common stock under dividend reinvestment, direct stock and employee stock purchase plans	1,344	0	1,344
Issuance of common stock under dividend reinvestment, direct stock and employee stock purchase plans (in shares)	73,517
Balance at Jun. 30, 2013	78,897	21,435	100,332
Balance (in shares) at Jun. 30, 2013	12,899,098
Balance at Dec. 31, 2013	80,545	22,966	103,511
Balance (in shares) at Dec. 31, 2013	12,979,281		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		12,827,367