Consolidated Statements Of Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]
BALANCE at Dec. 31, 2009	$ 247,609	$ 311	$ 431,846	$ (184,548)
BALANCE, shares at Dec. 31, 2009		31,100,433
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised for cash	690	3	687
Stock options exercised for cash, shares	266,433	266,433
Stock-based compensation	10,290		10,290
Restricted stock awards and units issued, net of forfeitures	(1,098)	3	(1,101)
Restricted stock awards and units issued, net of forfeitures, shares		344,311
Common stock offerings, net of offering costs	188,534	72	188,462
Common stock offerings, net of offering costs, shares		7,195,000
Other	661		661
Net income (loss)	9,950			9,950
BALANCE at Dec. 31, 2010	456,636	389	630,845	(174,598)
BALANCE, shares at Dec. 31, 2010		38,906,177
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised for cash	48	1	47
Stock options exercised for cash, shares	151,500	151,500
Stock-based compensation	14,444		14,444
Restricted stock awards and units issued, net of forfeitures	(479)	4	(483)
Restricted stock awards and units issued, net of forfeitures, shares		439,237
Other	2,577	1	2,576
Other, shares		65,762
Net income (loss)	36,629			36,629
BALANCE at Dec. 31, 2011	509,855	395	647,429	(137,969)
BALANCE, shares at Dec. 31, 2011		39,562,676
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised for cash	107	1	106
Stock options exercised for cash, shares	20,500	20,500
Stock-based compensation	17,396		17,396
Restricted stock awards and units issued, net of forfeitures	(80)	5	(85)
Restricted stock awards and units issued, net of forfeitures, shares		488,052
Other	2,251	1	2,250
Other, shares		93,289
Net income (loss)	55,487			55,487
BALANCE at Dec. 31, 2012	$ 585,016	$ 402	$ 667,096	$ (82,482)
BALANCE, shares at Dec. 31, 2012		40,164,517