Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income (loss)	$ (13,462)	$ 53,603	$ 36,178
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Impairment of inventory and rental equipment	20,372	0	0
Depreciation and amortization	18,024	17,848	15,109
Amortization of deferred financing costs	346	343	169
Accretion of debt discount	0	0	55
Provision for doubtful accounts	1,132	481	570
Provision for inventory reserves and market adjustments	0	358	1,330
Gain on sale of assets	(3,860)	(3,393)	(4,565)
Stock compensation expense	14,681	10,476	10,914
Deferred income tax (benefit) provision	(7,928)	1,502	793
Excess tax benefit related to share-based awards	(1,273)	(3,448)	(1,668)
Changes in current assets and liabilities:
Restricted cash	0	0	150
Accounts receivable	27,930	(13,773)	(9,860)
Inventories	(17,626)	(23,054)	4,529
Income taxes receivable	(4,700)	0	0
Other current assets	2,565	(5,602)	1,007
Accounts payable	(13,545)	13,154	(21,329)
Accrued liabilities	155	(1,174)	3,664
Income taxes payable	3,842	1,384	2,196
Interest payable	18	(18)	(5)
Net cash provided by operating activities	26,671	48,687	39,237
Cash flows from investing activities:
Capital expenditures	(20,468)	(19,907)	(15,007)
Proceeds from sale of assets	4,172	4,639	5,788
Payments for acquisitions, net of cash acquired	(1,250)	(5,704)	(53,396)
Purchase of patents and other intangible assets	(658)	(731)	(85)
Net cash used in investing activities	(18,204)	(21,703)	(62,700)
Cash flows from financing activities:
Repayments of indebtedness	(10,143)	(10,292)	(13,206)
Proceeds from borrowings	0	0	26,190
Borrowings on revolving credit facility	382,666	357,183	313,396
Repayments on revolving credit facility	(366,018)	(364,955)	(297,124)
Debt issuance costs	(10)	(399)	(1,293)
Issuance costs of preferred stock and detachable warrants	0	0	(200)
Excess tax benefit related to share-based awards	1,273	3,448	1,668
Purchase of treasury stock	(6,345)	(6,294)	(7,568)
Proceeds from sale of common stock	879	906	824
Repurchase of common stock	(9,697)	(10,395)	0
Proceeds from exercise of stock options	39	462	491
Proceeds from exercise of warrants	0	1,545	323
Proceeds from noncontrolling interest	7	351	0
Net cash (used in) provided by financing activities	(7,349)	(28,440)	23,501
Effect of changes in exchange rates on cash and cash equivalents	(176)	(8)	(8)
Net increase (decrease) in cash and cash equivalents	942	(1,464)	30
Cash and cash equivalents at beginning of year	1,266	2,730	2,700
Cash and cash equivalents at end of year	$ 2,208	$ 1,266	$ 2,730