Consolidated Statements of Cash Flows - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 47,451	$ 103,654	$ 76,238
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, accretion, and amortization	672,113	643,100	638,189
Non-cash asset impairment and decommission costs	26,192	32,423	25,693
Non-cash compensation expense	42,327	38,249	32,915
Amortization of deferred financing fees	20,289	21,940	21,136
Loss (gain) on remeasurement of U.S. denominated intercompany loan	89,101	8,754	(90,030)
Provision for doubtful accounts	551	2,909	22,516
Loss from extinguishment of deb, net	14,087	1,961	52,701
Other non-cash items reflected in the Statements of Operations	(14,586)	(4,850)	(1,225)
Changes in operating assets and liabilities, net of acquisitions:
AR and costs and est. earnings in excess of billings on uncompleted contracts, net	(29,427)	(20,893)	(7,270)
Prepaid expenses and other assets	(38,040)	(16,888)	(40,289)
Accounts payable and accrued expenses	(3,021)	3,555	(10,516)
Other liabilities	23,581	4,556	22,467
Net cash provided by operating activities	850,618	818,470	742,525
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisitions	(451,829)	(441,547)	(276,835)
Capital expenditures	(149,812)	(147,044)	(139,982)
Purchase of investments	(156,983)	(397)	(100)
Proceeds from sale of investments	150,890	231	712
Other investing activities	(10,613)	(16,350)	(12,030)
Net cash used in investing activities	(618,347)	(605,107)	(428,235)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings under Revolving Credit Facility	1,120,000	525,000	580,000
Repayments under Revolving Credit Facility	(835,000)	(875,000)	(190,000)
Repayment of Term Loans	(1,947,000)	(20,000)	(20,000)
Proceeds from issuance of Term Loans, net of fees	2,377,218
Proceeds from issuance of Senior Notes, net of fees		741,108	1,078,123
Proceeds from issuance of Tower Securities, net of fees	631,466	749,764	690,475
Repayment of Tower Securities	(755,000)	(610,000)	(550,000)
Repurchase and retirement of common stock	(795,581)	(854,534)	(545,689)
Other financing activities	55,360	49,088	8,394
Net cash used in financing activities	(148,537)	(294,574)	(288,557)
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	(9,729)	(464)	13,618
NET CHANGE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	74,005	(81,675)	39,351
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH:
Beginning of year	104,295	185,970	146,619
End of year	178,300	104,295	185,970
Cash paid during the period for:
Interest	376,628	319,562	338,409
Income taxes	21,645	14,653	9,655
SUPPLEMENTAL CASH FLOW INFORMATION OF NON-CASH ACTIVITIES:
Assets acquired through capital leases	$ 1,039	$ 254	1,386
Common stock issued in connection with acquisitions		63,313
5.625% Senior Notes [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Payment for the redemption of Senior Notes			(514,065)
5.75% Senior Notes [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Payment for the redemption of Senior Notes			$ (825,795)