Unaudited Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Revenue	$ 87,942	$ 116,761	$ 257,346	$ 324,653
Cost of revenue	56,715	70,683	170,340	192,585
Gross profit	31,227	46,078	87,006	132,068
Expenses:
Selling, general and administrative	23,634	21,499	70,223	63,924
Depreciation and amortization	2,785	2,439	8,258	7,225
Research and development	2,031	1,293	5,273	3,599
Impairment of inventory and rental equipment	0	0	20,372	0
Total expenses	28,450	25,231	104,126	74,748
Income (loss) from operations	2,777	20,847	(17,120)	57,320
Other income (expense):
Interest expense	(476)	(424)	(1,303)	(1,259)
Other income (expense), net	74	(87)	(154)	(306)
Total other income (expense)	(402)	(511)	(1,457)	(1,565)
Income (loss) before income taxes	2,375	20,336	(18,577)	55,755
Income tax (expense) benefit	(400)	(6,064)	6,490	(18,425)
Net income (loss)	$ 1,975	$ 14,272	$ (12,087)	$ 37,330
Earnings (loss) per common share:
Basic earnings (loss) per common share (in dollars per share)	$ 0.04	$ 0.26	$ (0.22)	$ 0.69
Diluted earnings (loss) per common share (in dollars per share)	$ 0.04	$ 0.26	$ (0.22)	$ 0.67
Weighted average common shares:
Weighted average common shares used in computing basic earnings (loss) per common share	54,578	54,789	54,430	54,464
Weighted average common shares used in computing diluted earnings (loss) per common share	54,947	55,690	54,430	55,536