Consolidated Statement Of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash Flows from Operating Activities
Net income	$ 54,318	$ 62,564
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	24,163	22,553
Deferred income taxes	(11,681)	(6,808)
Provision for uncollectible accounts receivable	8,211	7,303
Amortization of discount on convertible notes	6,450	6,028
Stock option expense	4,732	6,709
Amortization of debt issuance costs	1,421	940
Noncash long-term incentive compensation	1,161
Changes in operating assets and liabilities, excluding amounts acquired in business combinations:
Decrease/(increase) in accounts receivable	5,293	(30,409)
Decrease in inventories	329	1,029
Decrease/(increase) in prepaid expenses	(6,183)	1,554
Increase in accounts payable and other current liabilities	48,967	4,454
Increase in income taxes	1,923	1,292
Increase in other assets	(5,002)	(3,944)
Increase in other liabilities	3,978	6,648
Excess tax benefit on share-based compensation	(2,507)	(2,714)
Other sources	285	138
Net cash provided by operating activities	135,858	77,337
Cash Flows from Investing Activities
Capital expenditures	(18,887)	(26,489)
Business combinations, net of cash acquired	(2,210)	(5,900)
Other sources	139	528
Net cash provided/(used) by investing activities	(20,958)	(31,861)
Cash Flows from Financing Activities
Purchases of treasury stock	(89,611)	(11,724)
Dividends paid	(10,459)	(9,641)
Capital stock surrendered to pay taxes on stock-based compensation	(4,280)	(3,236)
Proceeds from exercise of stock options	13,125	10,483
Excess tax benefit on share-based compensation	2,507	2,714
Decrease in cash overdrafts payable	(10,928)	(3,299)
Debt issuance costs	(1,108)
Other sources/(uses)	(473)	442
Net cash provided/(used) by financing activities	(101,227)	(14,261)
Net increase/(decrease) in cash and cash equivalents	13,673	31,215
Cash and cash equivalents at beginning of year	69,531	38,081
Cash and cash equivalents at end of period	$ 83,204	$ 69,296