Condensed Consolidated Statement Of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income	$ 89,554	$ 109,281
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	118,597	88,569
Amortization of financing costs and discounts	9,094	7,224
Share-based compensation	13,740	9,947
Provision for doubtful accounts	9,099	9,072
Deferred income taxes	3,859	(2,328)
Gain (Loss) on Extinguishment of Debt	7,962	0
Gain (Loss) on Disposition of Business	(4,715)	0
Decrease (increase) in:
Accounts receivable	4,711	(7,631)
Prepaid expenses and other current assets	(264)	(663)
Other assets	134	(7,947)
(Decrease) increase in:
Accounts payable and accrued expenses	(49,324)	(4,601)
Income taxes payable	(26,359)	(927)
Deferred revenue	(75)	(4,134)
Liability for uncertain tax positions	1,554	8,502
Other	1,429	(11,824)
Net cash provided by operating activities	178,996	192,540
Cash flows from investing activities:
Maturity of available-for-sale investments	0	145,005
Purchase of available-for-sale investments	(5)	(75,834)
Purchases of property and equipment	(29,483)	(17,447)
Acquisition of businesses, net of cash received	(47,268)	(91,401)
Proceeds from Divestiture of Businesses	33,508	0
Purchases of intangible assets	(1,320)	(2,014)
Net cash used in investing activities	(44,568)	(41,691)
Cash flows from financing activities:
Proceeds from Issuance of Long-term Debt	636,598	0
Repayments of Long-term Debt	(255,000)	0
Proceeds from Lines of Credit	44,981	0
Repayments of Lines of Credit	(225,000)	0
Repurchases of common stock and restricted stock	(7,862)	(56,083)
Issuance of common stock under employee stock purchase plan	194	191
Exercise of stock options	1,108	3,272
Dividends paid	(54,346)	(48,768)
Deferred payments for acquisitions	(5,062)	(18,939)
Proceeds from (Payments for) Other Financing Activities	(45)	1,680
Net cash provided by (used in) financing activities	135,566	(118,647)
Effect of exchange rate changes on cash and cash equivalents	8,600	(2,169)
Net change in cash and cash equivalents	278,594	30,033
Cash and cash equivalents at beginning of period	123,950	255,530
Cash and cash equivalents at end of period	$ 402,544	$ 285,563