Consolidated Statement 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	$ 62,564	$ 60,274
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	22,553	22,202
Deferred income taxes	(6,808)	(1,608)
Provision for uncollectible accounts receivable	7,303	6,640
Amortization of discount on convertible notes	6,028	5,633
Stock option expense	6,709	6,903
Noncash long-term incentive compensation		2,595
Changes in operating assets and liabilities, excluding amounts acquired in business combinations:
Increase in accounts receivable	(30,409)	(5,991)
Decrease/(increase) in inventories	1,029	(1,160)
Decrease in prepaid expenses	1,554	254
Increase in accounts payable and other current liabilities	4,454	2,654
Increase in income taxes	1,292	12,253
Increase in other assets	(3,944)	(3,811)
Increase in other liabilities	6,648	3,567
Excess tax benefit on share-based compensation	(2,714)	(3,368)
Other sources	1,078	899
Net cash provided by operating activities	77,337	107,936
Cash Flows from Investing Activities
Capital expenditures	(26,489)	(23,459)
Business combinations, net of cash acquired	(5,900)	(3,689)
Other sources/(uses)	528	(829)
Net cash used by investing activities	(31,861)	(27,977)
Cash Flows from Financing Activities
Dividends paid	(9,641)	(9,393)
Purchases of treasury stock	(15,047)	(110,288)
Proceeds from issuance of capital stock	10,483	7,979
Excess tax benefit on share-based compensation	2,714	3,368
Increase/(decrease) in cash overdrafts payable	(3,299)	2,297
Debt issuance costs		(2,723)
Other sources	529	226
Net cash used by financing activities	(14,261)	(108,534)
Increase/(Decrease) in Cash and Cash Equivalents	31,215	(28,575)
Cash and cash equivalents at beginning of year	38,081	49,917
Cash and cash equivalents at end of period	$ 69,296	$ 21,342