CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net income	$ 9,490	$ 8,636
Adjustments to reconcile net income to net cash provided by operating activities:
Loss on disposal of assets	52
Reduction of seller notes and earnouts		(177)
Provision for doubtful accounts	5,229	4,723
Depreciation and amortization	9,285	8,285
Amortization of debt issuance costs	864	863
Compensation expense on stock options and restricted stock units	1,667	1,971
Changes in operating assets and liabilities, net of effects of acquired companies:
Accounts receivable	3,644	851
Inventories	(5,197)	(7,868)
Prepaid expenses, other current assets, and income taxes	(3,860)	(2,443)
Accounts payable	(2,006)	(522)
Accrued expenses and accrued interest payable	3,883	4,294
Accrued compensation related costs	(19,544)	(17,504)
Other	(1,314)	183
Net cash provided by operating activities	2,193	1,292
Cash flows from investing activities:
Purchase of property, plant and equipment (net of acquisitions)	(5,110)	(4,777)
Purchase of equipment leased to third parties under operating leases	(288)	(539)
Acquisitions and contingent considerations (net of cash acquired)		(2,402)
Restricted cash		(3,120)
Proceeds from sale of property, plant and equipment	91
Net cash used in investing activities	(5,307)	(10,838)
Cash flows from financing activities:
Repayment of term loan	(750)	(1,450)
Scheduled repayment of seller's notes	(1,410)	(488)
Repayment of capital lease obligations	(180)
Excess tax benefit from stock-based compensation	1,214	209
Proceeds from issuance of common stock	62	627
Net cash used in financing activities	(1,064)	(1,102)
Decrease in cash and cash equivalents	(4,178)	(10,648)
Cash and cash equivalents, at beginning of period	19,211	42,896
Cash and cash equivalents, at end of period	$ 15,033	$ 32,248