CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
OPERATING ACTIVITIES:
Net income	$ 237,343	$ 210,457	$ 176,389
Adjustments to reconcile net income to net cash provided by operating activities:
Loss/ (gain) on sale of business	19	(2,955)	0
Restructuring and plant closure costs	2,756	5,571	1,609
Write down of other assets	1,256	0	0
Change in fair value of contingent consideration	(7,221)	0	0
Accelerated amortization of term loan financing fees	1,241	0	0
Stock compensation expense	15,367	15,298	14,638
Excess tax benefit of stock options exercised	(17,410)	(24,687)	(10,905)
Depreciation	49,777	43,966	34,600
Amortization	16,269	9,919	5,390
Deferred income taxes	31,837	26,312	22,253
Changes in operating assets and liabilities, net of effect of acquisitions and divestitures:
Accounts receivable	(31,821)	(20,270)	12,567
Accounts payable	(12,539)	(165)	2,420
Accrued liabilities	21,656	56,578	21,464
Deferred revenues	(1,997)	(878)	89
Other assets and liabilities	(429)	6,524	(3,268)
Net cash provided by operating activities	306,104	325,670	277,246
INVESTING ACTIVITIES:
Payments for acquisitions, net of cash acquired	(479,661)	(190,430)	(311,891)
Proceeds from/(purchases of) short-term investments	15,942	(14,732)	385
Proceeds from sale of business and other assets	2,371	8,000	1,227
Capital expenditures	(53,301)	(48,320)	(39,910)
Net cash used in investing activities	(514,649)	(245,482)	(350,189)
FINANCING ACTIVITIES:
Repayment of long-term debt and other obligations	(39,536)	(42,377)	(19,023)
Borrowings on senior credit facility	1,643,458	1,007,801	963,061
Repayments on senior credit facility	(1,372,631)	(1,350,597)	(1,022,666)
Proceeds from private placement of long-term note	0	400,000	0
Proceeds from term loan	0	0	215,000
Payments of deferred financing costs	(3,740)	(5,757)	(3,635)
Payments on capital lease obligations	(3,333)	(2,894)	(1,106)
Purchase and cancellation of treasury stock	(124,056)	(94,335)	(75,686)
Payments to noncontrolling interests	(534)	0	0
Proceeds from other issuance of common stock	31,286	49,907	14,922
Excess tax benefit of stock options exercised	17,410	24,687	10,905
Net cash provided by/(used in) financing activities	148,324	(13,565)	81,772
Effect of exchange rate changes on cash	3,456	(3,114)	(2,157)
Net (decrease)/increase in cash and cash equivalents	(56,765)	63,509	6,672
Cash and cash equivalents at beginning of year	79,276	15,767	9,095
Cash and cash equivalents at end of year	22,511	79,276	15,767
NON-CASH ACTIVITIES:
Net issuance of obligations for acquisitions	$ 58,338	$ 96,295	$ 38,090