Note 13 - Selected Quarterly Financial Data (Unaudited) (Detail) - Unaudited Quarterly Financial Data (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenues (in Dollars)	$ 256,795	$ 246,218	$ 224,985	$ 210,587	$ 246,016	$ 239,585	$ 230,192	$ 199,182	$ 938,585	$ 914,975	$ 726,866
Gross profit (in Dollars)	63,481	52,629	45,840	41,174	60,282	61,419	59,199	48,680	203,124	229,580	190,591
Operating income (in Dollars)	21,710	9,498	7,840	5,489	24,827	26,955	22,747	12,506	44,537	87,035	49,117
Income from continuing operations (in Dollars)					17,421	18,826	15,805	8,510	27,670	61,980	31,395
Loss from discontinued operations (in Dollars)					(7)	(16)	(28)	(49)		(100)	(4,070)
Net income (in Dollars)	$ 14,752	$ 1,160	$ 7,629	$ 3,006	$ 17,414	$ 18,810	$ 15,777	$ 8,461	$ 27,670	$ 61,880	$ 27,325
Basic earnings per share:
Income from continuing operations					$ 0.44	$ 0.48	$ 0.40	$ 0.22	$ 0.67	$ 1.55	$ 0.81
Loss from discontinued operations					$ 0.00	$ 0.00	$ 0.00	$ 0.00		$ (0.01)	$ (0.11)
Net income	$ 0.37	$ 0.03	$ 0.19	$ 0.08	$ 0.44	$ 0.48	$ 0.40	$ 0.22	$ 0.67	$ 1.54	$ 0.70
Diluted earnings per share
Income from continuing operations					$ 0.44	$ 0.48	$ 0.40	$ 0.22	$ 0.67	$ 1.54	$ 0.81
Loss from discontinued operations					$ 0.00	$ 0.00	$ 0.00	$ 0.00		$ (0.01)	$ (0.11)
Net income	$ 0.37	$ 0.03	$ 0.19	$ 0.08	$ 0.44	$ 0.48	$ 0.40	$ 0.22	$ 0.67	$ 1.53	$ 0.70