CONSOLIDATED STATEMENT OF CHANGES IN COMMON STOCK EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Common Stock [Member]	Treasury Stock [Member]	Other Paid-in Capital [Member]	Accumulated Other Comprehensive Loss, net of tax [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2008	$ 82,504	$ (49,501)	$ 71,489	$ (228)	$ 115,215	$ 219,479
Balance (in shares) at Dec. 31, 2008	13,750,717	(2,175,892)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					20,749	20,749
Other comprehensive income, net of tax				19		19
Common stock issuance costs			(179)			(179)
Dividend reinvestment plan	117	1,065	255			1,437
Dividend reinvestment plan (in shares)	19,468	46,819
Stock options exercised	217		284			501
Stock options exercised (in shares)	36,160
Share-based compensation:
Common & nonvested shares	27		58			85
Common & nonvested shares (in shares)	4,530
Performance share plans	151		417			568
Performance share plans (in shares)	25,093
Dividends declared:
Common					(10,720)	(10,720)
Cumulative non-redeemable preferred stock					(368)	(368)
Amortization of preferred stock issuance expense			16			16
Gain (loss) on capital stock			(161)		(3)	(164)
Balance at Dec. 31, 2009	83,016	(48,436)	72,179	(209)	124,873	231,423
Balance (in shares) at Dec. 31, 2009	13,835,968	(2,129,073)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					20,954	20,954
Other comprehensive income, net of tax				(23)		(23)
Common stock issuance costs	8,992		20,621			29,613
Common stock issuance, net of issuance costs (in shares)	1,498,745
Dividend reinvestment plan	415		972			1,387
Dividend reinvestment plan (in shares)	69,234
Stock options exercised	272		432			704
Stock options exercised (in shares)	45,300
Share-based compensation:
Common & nonvested shares	35		88			123
Common & nonvested shares (in shares)	5,849
Performance share plans	91		152			243
Performance share plans (in shares)	15,121
Dividends declared:
Common					(11,344)	(11,344)
Cumulative non-redeemable preferred stock					(368)	(368)
Amortization of preferred stock issuance expense			16			16
Gain (loss) on capital stock			2		(2)	0
Balance at Dec. 31, 2010	92,821	(48,436)	94,462	(232)	134,113	272,728
Balance (in shares) at Dec. 31, 2010	15,470,217	(2,129,073)				13,341,144
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					5,704	5,704
Other comprehensive income, net of tax				46		46
Dividend reinvestment plan	269		941			1,210
Dividend reinvestment plan (in shares)	44,801
Stock options exercised	304		596			900
Stock options exercised (in shares)	50,677
Share-based compensation:
Common & nonvested shares	52		317			369
Common & nonvested shares (in shares)	8,627
Performance share plans	167		(292)			(125)
Performance share plans (in shares)	27,769
Dividends declared:
Common					(12,326)	(12,326)
Cumulative non-redeemable preferred stock					(368)	(368)
Amortization of preferred stock issuance expense			16			16
Balance at Dec. 31, 2011	$ 93,613	$ (48,436)	$ 96,040	$ (186)	$ 127,123	$ 268,154
Balance (in shares) at Dec. 31, 2011	15,602,091	(2,129,073)				13,473,018