Condensed Consolidating Balance Sheet (Unaudited) (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
ASSETS
Cash and cash equivalents	$ 93,625			$ 52,183
Restricted cash	11,103
Accounts receivable, net of allowance	234,162			254,188
Prepaid expenses and other current assets	27,965			21,119
Total current assets	366,855			327,490
Property and equipment, net	3,023,963			2,802,449
Goodwill	43,996			40,927
Non-current deferred tax assets	14,309			12,814
Other assets	134,909			88,718
Total assets	3,584,032			3,272,398
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable and accrued expenses	307,689			277,804
Income taxes payable	1,375			3,034
Current portion of long-term debt	12,795			10,000
Total current liabilities	321,859			290,838
Long-term debt, net	1,752,185			1,437,187
Deferred revenue	29,510			39,735
Other liabilities	58,403			53,030
Total liabilities	2,161,957			1,820,790
Total stockholders' equity	1,422,075	$ 1,427,918	$ 1,434,210	1,451,608	$ 1,458,681	$ 1,463,344	$ 1,463,161	$ 1,458,963
Total liabilities and stockholders' equity	3,584,032			3,272,398
Reportable Legal Entities | Parent
ASSETS
Cash and cash equivalents	68,599			25,745
Accounts receivable, net of allowance	143,538			211,673
Prepaid expenses and other current assets	2,929			1,835
Total current assets	215,066			239,253
Property and equipment, net	2,470,164			2,467,166
Goodwill	33,057			26,031
Other assets	608,586			421,474
Total assets	3,326,873			3,153,924
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable and accrued expenses	312,080			251,011
Income taxes payable	321			1,443
Current portion of long-term debt	7,456			10,000
Total current liabilities	319,857			262,454
Long-term debt, net	1,569,543			1,437,982
Non-current deferred tax liabilities	471			379
Other liabilities	14,927			1,501
Total liabilities	1,904,798			1,702,316
Total stockholders' equity	1,422,075			1,451,608
Total liabilities and stockholders' equity	3,326,873			3,153,924
Reportable Legal Entities | Combined Subsidiary Guarantors
ASSETS
Cash and cash equivalents	24,664			26,438
Accounts receivable, net of allowance	449,928			372,755
Prepaid expenses and other current assets	27,498			24,986
Total current assets	502,090			424,179
Property and equipment, net	314,981			335,283
Goodwill	10,939			14,896
Non-current deferred tax assets	14,780			13,193
Other assets	51,269			69,117
Total assets	894,059			856,668
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable and accrued expenses	352,062			362,701
Income taxes payable	1,054			1,591
Total current liabilities	353,116			364,292
Long-term debt, net	114,373			114,205
Deferred revenue	29,510			39,735
Other liabilities	43,476			51,529
Total liabilities	540,475			569,761
Total stockholders' equity	353,584			286,907
Total liabilities and stockholders' equity	894,059			856,668
Reportable Legal Entities | Non-Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	362
Restricted cash	11,103
Accounts receivable, net of allowance	2,802
Prepaid expenses and other current assets	2,943
Total current assets	17,210
Property and equipment, net	238,818
Other assets	38,669
Total assets	294,697
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable and accrued expenses	11,023
Current portion of long-term debt	5,339
Total current liabilities	16,362
Long-term debt, net	183,269
Total liabilities	199,631
Total stockholders' equity	95,066
Total liabilities and stockholders' equity	294,697
Consolidating Adjustments and Other
ASSETS
Accounts receivable, net of allowance	(362,106)			(330,240)
Prepaid expenses and other current assets	(5,405)			(5,702)
Total current assets	(367,511)			(335,942)
Non-current deferred tax assets	(471)			(379)
Other assets	(563,615)			(401,873)
Total assets	(931,597)			(738,194)
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable and accrued expenses	(367,476)			(335,908)
Total current liabilities	(367,476)			(335,908)
Long-term debt, net	(115,000)			(115,000)
Non-current deferred tax liabilities	(471)			(379)
Total liabilities	(482,947)			(451,287)
Total stockholders' equity	(448,650)			(286,907)
Total liabilities and stockholders' equity	$ (931,597)			$ (738,194)