Note 12 - 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, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues	$ 274,683	$ 265,155	$ 257,531	$ 230,594	$ 256,795	$ 246,218	$ 224,985	$ 210,587	$ 1,027,963	$ 938,585	$ 914,975
Gross profit	65,224	62,774	62,427	52,684	63,481	52,629	45,840	41,174	243,109	203,124	229,580
Operating income	23,718	26,142	18,363	10,899	21,710	9,498	7,840	5,489	79,122	44,537	87,035
Net income	$ 14,895	$ 19,544	$ 11,498	$ 6,724	$ 14,752	$ 1,160	$ 7,629	$ 3,006	$ 56,849	$ 27,670	$ 61,880
Basic earnings per share:
Net income (in Dollars per share)	$ 0.38	$ 0.50	$ 0.29	$ 0.17	$ 0.37	$ 0.03	$ 0.19	$ 0.08	$ 1.34	$ 0.67	$ 1.54
Diluted earnings per share
Net income (in Dollars per share)	$ 0.38	$ 0.49	$ 0.29	$ 0.17	$ 0.37	$ 0.03	$ 0.19	$ 0.08	$ 1.33	$ 0.67	$ 1.53