CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income	$ 63,584	$ 63,692	$ 54,477
Adjustments to reconcile net income to net cash provided by operating activities:
Loss/(gain) on disposals of assets	(5,914)	64	7
Reduction of seller notes and earnouts	(1,032)	(993)	(541)
Provision for doubtful accounts	14,330	9,589	9,396
Provision (benefit) for deferred income taxes	(1,602)	(4,303)	8,439
Depreciation and amortization	37,486	34,652	30,969
Amortization of debt issuance costs	2,488	3,452	3,334
Loss on extinguishment of debt	6,645
Compensation expense restricted stock units	9,080	8,061	8,088
Changes in operating assets and liabilities, net of effects of acquired companies:
Accounts receivable	(32,060)	(30,259)	(26,583)
Inventories	(11,329)	(12,827)	(14,072)
Prepaid expenses, other current assets, and income taxes	4,689	3,867	796
Accounts payable	6,235	(2,114)	(5,902)
Accrued expenses, accrued interest payable	(223)	3,501	(1,424)
Accrued compensation related costs	(7,379)	4,348	(7,404)
Other	1,262	589	2,224
Net cash provided by operating activities	86,260	81,319	61,804
Cash flows from investing activities:
Purchase of property, plant and equipment (net of acquisitions)	(34,236)	(29,492)	(25,300)
Purchase of equipment leased to third parties under operating leases	(4,210)	(3,671)	(3,374)
Acquisitions and contingent considerations (net of cash acquired)	(9,296)	(62,500)	(14,842)
Restricted cash	3,120	(3,120)
Purchase of company-owned life insurance investment		(2,000)	(4,000)
Proceeds from sale of property, plant and equipment	8,684	1,732	646
Net cash used in investing activities	(35,938)	(99,051)	(46,870)
Cash flows from financing activities:
Borrowings under revolving credit agreement	249,000		10,000
Repayments under revolving credit agreement	(224,000)		(10,000)
Borrowings under term loan	225,000
Repayment of term loan	(296,113)	(3,700)	(3,000)
Scheduled repayment of seller's notes	(12,410)	(5,255)	(4,151)
Repayment of capital lease obligations	(1,047)	(713)
Deferred financing costs	(3,667)		(4,230)
Excess tax benefit from stock based compensation	3,501	1,505	2,462
Proceeds from issuance of common stock	2,437	3,560	2,680
Purchase and retirement of treasury stock	(2,374)	(1,350)	(2,107)
Net cash used in financing activities	(59,673)	(5,953)	(8,346)
Increase (decrease) in cash and cash equivalents	(9,351)	(23,685)	6,588
Cash and cash equivalents, at beginning of year	19,211	42,896	36,308
Cash and cash equivalents, at end of year	$ 9,860	$ 19,211	$ 42,896