Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities
Net income	$ 370,930	$ 93,764	$ 366,186
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	239,998	264,742	264,879
Loss on impairment of assets	13,110	40,597	23,465
Gain on sale of subsidiaries and disposal of property and equipment, net	(292,108)	(5,837)	(408,672)
(Gain) loss on derivative instruments	(89,143)	(29,278)	4,717
Proceeds from settlement of derivative contracts	14,117	0	0
Loss on debt extinguishment	7,481	8,392	17,363
Non-cash interest expense	15,408	49,582	46,195
Interest paid on deferred purchase price for acquisitions	(4,463)	(39,419)	0
Non-cash share-based compensation expense	10,791	64,788	38,809
Bad debt expense	112,440	124,308	108,019
Deferred income taxes	(7,474)	(164,785)	(30,150)
Unrealized foreign currency exchange loss (gain)	37,796	4,135	(67,946)
Non-cash loss (gain) from non-income tax contingencies	6,839	(2,883)	17,360
Other, net	(10,297)	3,463	5,949
Changes in operating assets and liabilities:
Receivables	(83,316)	(129,335)	(110,693)
Prepaid expenses and other assets	(39,347)	(60,051)	(17,594)
Accounts payable and accrued expenses	(7,512)	(30,407)	688
Income tax receivable/payable, net	48,875	(10,695)	(36,762)
Deferred revenue and other liabilities	52,733	11,076	(29,557)
Net cash provided by operating activities	396,858	192,157	192,256
Cash flows from investing activities
Purchase of property and equipment	(238,046)	(274,063)	(240,258)
Expenditures for deferred costs	(19,866)	(19,717)	(16,436)
Receipts from sale of subsidiaries and property and equipment, net of cash sold	375,807	9,831	554,441
Settlement of derivatives related to sale of subsidiaries	(9,960)	0	(5,663)
Proceeds from corporate-owned life insurance and property insurance recoveries	27,356	370	3,623
Business acquisitions, net of cash acquired	(17,019)	(835)	0
Investments in affiliates and payments (to) from related parties	(2,778)	(268)	1,590
Net cash provided by (used in) investing activities	115,494	(284,682)	297,297
Cash flows from financing activities
Proceeds from issuance of long-term debt, net of original issue discount	485,470	2,898,836	708,827
Payments on long-term debt	(867,915)	(3,038,946)	(1,421,379)
Payments of deferred purchase price for acquisitions	(13,650)	(94,891)	(22,236)
Payments to purchase noncontrolling interests	(127)	(17,443)	(25,665)
Proceeds from issuance of convertible redeemable preferred stock, net of issuance costs	0	55,290	329,142
Payment of dividends on Series A Preferred Stock and to noncontrolling interests	(11,103)	(19,371)	(1,505)
Proceeds from initial public offering, net of issuance costs	0	456,359	0
Proceeds from exercise of stock options	0	0	253
Withholding of shares to satisfy tax withholding for vested stock awards and exercised stock options	(2,528)	(2,151)	(1,725)
Payments of debt issuance costs and redemption and call premiums for debt modification	(587)	(81,242)	(11,582)
Noncontrolling interest holder's loan to subsidiaries	0	943	802
Distributions from (to) noncontrolling interest holders	311	186	(654)
Net cash (used in) provided by financing activities	(410,129)	157,570	(445,722)
Effects of exchange rate changes on Cash and cash equivalents and Restricted cash	(13,486)	25,909	3,478
Change in cash included in current assets held for sale	(31,729)	(32,509)	(3,492)
Net change in Cash and cash equivalents and Restricted cash	57,008	58,445	43,817
Cash and cash equivalents and Restricted cash at beginning of period	532,782	474,337	430,520
Cash and cash equivalents and Restricted cash at end of period	$ 589,790	$ 532,782	$ 474,337