CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash flows from operating activities:
Net income	$ 42,285	$ 37,056
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Loss (gain) on disposal of assets	5	(6)
Reduction of seller notes and earnouts	(971)	(321)
Provision for bad debts	15,926	17,291
Provision for deferred income taxes	(1,031)	(446)
Depreciation and amortization	25,432	22,852
Amortization of debt issuance costs	2,589	2,470
Compensation expense on restricted stock	6,100	6,014
Excess tax benefit from stock-based compensation	(685)	(975)
Changes in operating assets and liabilities, net of effects of acquired companies:
Accounts receivable	(19,612)	(23,551)
Inventories	(12,214)	(11,584)
Prepaid expenses, other current assets, and income taxes	348	8,615
Accounts payable	670	(6,757)
Accrued expenses and accrued interest payable	3,492	2,142
Accrued compensation related costs	(5,970)	(19,816)
Other	2,643	2,166
Net cash provided by operating activities	59,007	35,150
Cash flows from investing activities:
Purchase of property, plant and equipment (net of acquisitions)	(23,439)	(18,879)
Purchase of equipment leased to third parties under operating leases	(1,438)	(2,875)
Acquisitions and contingent purchase price (net of cash acquired)	(14,266)	(10,868)
Proceeds from sale of property, plant and equipment		94
Restricted cash	(3,120)
Net cash used in investing activities	(42,263)	(32,528)
Cash flows from financing activities:
Borrowings under revolving credit agreement		10,000
Repayment under revolving credit agreement		(10,000)
Repayment of term loan	(2,950)	(2,250)
Repayment of long-term debt	(3,416)	(2,561)
Repayment of capital lease obligations	(545)
Deferred financing costs		(4,230)
Excess tax benefit from stock-based compensation	685	975
Proceeds from issuance of common stock	2,206	573
Net cash used in financing activities	(4,020)	(7,493)
Decrease in cash and cash equivalents	12,724	(4,871)
Cash and cash equivalents, at beginning of period	42,896	36,308
Cash and cash equivalents, at end of period	$ 55,620	$ 31,437