Consolidated Statement of Changes in Shareholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Preferred stock	Common stock	Capital in excess of par value	Retained earnings	Accumulated other comprehensive income
Beginning Balance at Dec. 31, 2011	$ 145,276		$ 26	$ 48,944	$ 98,426	$ (2,120)
Beginning Balance, shares at Dec. 31, 2011			25,756
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued, other comp, shares			51
Shares issued, ESPP	333			333
Shares issued, ESPP, shares			30
Shares issued, shared distribution	4,407			4,407
Shares issued, shared distribution, shares			145
Stock-based compensation	2,087			2,087
Dividends declared	(7,788)				(7,788)
Net income	21,870				21,870
Other comprehensive income (loss)	(215)					(215)
Ending Balance at Jun. 30, 2012	$ 165,970		$ 26	$ 55,771	$ 112,508	$ (2,335)
Ending Balance, shares at Jun. 30, 2012			25,982