Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
CASH FLOWS PROVIDED BY OPERATING ACTIVITIES:
Net income	$ 98,860	$ 77,534
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation	57,217	57,458
Amortization	35,599	39,944
Provision for share-based compensation	11,532	13,841
Deferred income tax expense (benefit)	8,010	(3,755)
Amortization of deferred financing costs	3,751	44,053
Increase in acquisition contingent consideration	645	644
(Gain) loss on sale of property and equipment	135	(12,607)
Changes in operating assets and liabilities, net of business acquisitions
Accounts receivable	(34,560)	(13,957)
Other assets	(3,751)	6,852
Accounts payable	(4,270)	(10,830)
Accrued wages and benefits	(928)	4,168
Accrued interest	(1,706)	(8,420)
Other liabilities and income tax payable	(10,488)	2,560
Net cash flows provided by operating activities	160,046	197,485
CASH FLOWS USED IN INVESTING ACTIVITIES:
Business acquisitions	(29,882)	(9,745)
Purchases of property and equipment	(53,248)	(73,864)
Proceeds from the sale of property and equipment	409	38,368
Other	2,728	2,657
Net cash flows used in investing activities	(79,993)	(42,584)
CASH FLOWS USED IN FINANCING ACTIVITIES:
Payments on notes and term loan facilities	(26,638)	(2,286,906)
Proceeds from term loan facilities	0	1,780,000
Proceeds from issuance of notes	0	400,000
Proceeds from issuance of long-term revolving credit obligations	34,000	85,000
Payments on long-term revolving credit obligations	(68,000)	(10,000)
Debt issuance costs	(102)	(25,273)
Proceeds from stock options and ESPP shares	2,847	3,927
Dividends paid	(18,754)	(37,333)
Repurchase of common stock	0	(21,961)
Net cash flows used in financing activities	(76,647)	(112,546)
EFFECT OF EXCHANGE RATES ON CASH AND CASH EQUIVALENTS	5,370	(1,278)
NET CHANGE IN CASH AND CASH EQUIVALENTS	8,776	41,077
CASH AND CASH EQUIVALENTS, Beginning of period	183,059	182,338
CASH AND CASH EQUIVALENTS, End of period	$ 191,835	$ 223,415