Consolidated Statements Of Changes In Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Common Stock [Member]	Series C Preferred Stock [Member] Accumulated Earnings [Member]	Series C Preferred Stock [Member]	Series D Preferred Stock [Member] Accumulated Earnings [Member]	Series D Preferred Stock [Member]	Treasury Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Total
Balance at Dec. 31, 2008	$ 188						$ 175,163	$ 79,660	$ 845	$ 255,856
Balance, shares at Dec. 31, 2008	18,856,602
Comprehensive income:
Net income								47,563		47,563
Other comprehensive income:
Change in unrealized gains, net of tax									1,131	1,131
Change in deferred tax valuation allowance									752	752
Comprehensive income										49,446
Common stock issued upon exercise of options	1						295			296
Common stock issued upon exercise of options, shares	32,800
Restricted common stock issued							131			131
Restricted common stock issued, shares	5,844
Share-based compensation							1,233			1,233
Tax benefit of share-based compensation							46			46
Redemption of Series preferred stock		(175)	(175)	(700)	(700)
Balance at Dec. 31, 2009	189						176,868	126,348	2,728	306,133
Balance, shares at Dec. 31, 2009	18,895,246
Comprehensive income:
Net income								34,606		34,606
Other comprehensive income:
Change in unrealized gains, net of tax									(1,748)	(1,748)
Change in deferred tax valuation allowance									(715)	(715)
Comprehensive income										32,143
Common stock issued upon exercise of options	2						1,453			1,455
Common stock issued upon exercise of options, shares	153,157
Restricted common stock issued							163			163
Restricted common stock issued, shares	12,246
Share-based compensation							2,162			2,162
Tax benefit of share-based compensation							238			238
Purchase of Treasury Stock Common						(12,102)				(12,102)
Purchase of Treasury Stock Common, shares						(708,608)
Balance at Dec. 31, 2010	191					(12,102)	180,884	160,954	265	330,192
Balance, shares at Dec. 31, 2010	19,060,649					708,608
Comprehensive income:
Net income								24,125		24,125
Other comprehensive income:
Change in unrealized gains, net of tax									1,986	1,986
Change in deferred tax valuation allowance									(36)	(36)
Comprehensive income										26,075
Common stock issued upon exercise of options	3						3,336			3,339
Common stock issued upon exercise of options, shares	338,350
Restricted common stock issued							210			210
Restricted common stock issued, shares	9,513
Share-based compensation							261			261
Tax benefit of share-based compensation							1,043			1,043
Purchase of Treasury Stock Common						(10,268)				(10,268)
Purchase of Treasury Stock Common, shares						(549,642)
Balance at Dec. 31, 2011	$ 194					$ (22,370)	$ 185,734	$ 185,079	$ 2,215	$ 350,852
Balance, shares at Dec. 31, 2011	19,408,512					1,258,250