Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows from Operating Activities:
Net income	$ 451,959	$ 406,815	$ 296,007
Adjustments to reconcile net income to net cash provided by operating activities —
Depreciation	225,256	218,107	202,519
Amortization of intangible assets	76,704	62,091	43,994
Asset impairment charges	8,282	13,892	49,375
Impairment of cost method investment	9,311	0	0
Change in fair value of contingent consideration liabilities	719	13,404	(11,248)
Equity in (earnings) losses of unconsolidated affiliates	(1,309)	(76,801)	52,867
Amortization of debt discount and issuance costs	5,126	1,870	1,270
(Gain) loss on sale of property and equipment	(3,056)	(5,797)	3,296
Provision for credit losses	3,656	11,249	7,169
Deferred income tax expense (benefit)	(60,016)	(7,919)	61,974
Non-cash stock-based compensation	91,641	52,013	52,484
Foreign currency and other (gain) loss and other non-cash items	(5,159)	(5,568)	(385)
Payments for contingent consideration liabilities	(14,506)	0	0
Changes in operating assets and liabilities, net of non-cash transactions	327,369	(156,805)	(400,533)
Net cash provided by operating activities	1,115,977	526,551	358,789
Cash Flows from Investing Activities:
Capital expenditures	(260,052)	(261,762)	(293,595)
Proceeds from sale of property and equipment	35,390	31,142	31,780
Proceeds from insurance settlements related to property and equipment	542	1,964	714
Cash paid for acquisitions, net of cash, cash equivalents and restricted cash acquired	(292,573)	(387,966)	(94,917)
Proceeds from disposition of businesses	18,785	0	0
Investments in unconsolidated affiliates and other entities	(14,856)	(47,056)	(36,909)
Cash received from investments in unconsolidated affiliates and other entities	13,963	46,590	4,705
Cash paid for intangible assets	(522)	(508)	(14,448)
Net cash used in investing activities	(499,323)	(617,596)	(402,670)
Cash Flows from Financing Activities:
Borrowings under credit facility	2,983,529	6,175,558	4,491,782
Payments under credit facility	(4,187,645)	(5,903,069)	(4,076,460)
Proceeds from notes offering	990,130	0	0
Payments on other long-term debt	(2,970)	(2,203)	(1,298)
Net borrowings (repayments) of short-term debt	(4,846)	(28,292)	33,790
Debt issuance and amendment costs	(11,089)	(2,309)	(1,976)
Payments for contingent consideration liabilities	(61,483)	0	0
Distributions to non-controlling interests, net of contributions received	(5,404)	(2,526)	(4,038)
Payments related to tax withholding for share-based compensation	(25,447)	(16,144)	(15,218)
Payments of dividends	(28,891)	(23,236)	0
Repurchase of common stock	(247,249)	(20,092)	(443,152)
Net cash provided by (used in) financing activities	(601,365)	177,687	(16,570)
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash	1,774	(153)	(68)
Net increase (decrease) in cash, cash equivalents and restricted cash	17,063	86,489	(60,519)
Cash, cash equivalents and restricted cash, beginning of year	169,745	83,256	143,775
Cash, cash equivalents and restricted cash, end of year	$ 186,808	$ 169,745	$ 83,256