SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION - Condensed Consolidating Statement of Cash Flows (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Condensed Financial Statements Captions [Line Items]
Net cash provided by operating activities	$ (31,572)	$ 15,404
Cash Flows From Investing Activities:
Cash paid for acquisitions and capital expenditures, net of proceeds from divestitures and asset sales	(3,588)	(8,459)
Net cash used in investing activities	(3,588)	(8,459)
Cash Flows From Financing Activities:
Proceeds from issuance of redeemable convertible preferred units, net	57,500
Net borrowings and repayments of debt	38,904	3,984
Other financing activities	(17,437)	(2,771)
Net cash provided by financing activities	78,967	1,213
Net increase in cash, cash equivalents and restricted cash	43,807	8,158
Cash, cash equivalents and restricted cash—Beginning of period	18,147	6,821
Cash, cash equivalents and restricted cash—End of period	61,954	14,979
Parent
Cash Flows From Investing Activities:
Payments to affiliates	(57,500)
Net cash used in investing activities	(57,500)
Cash Flows From Financing Activities:
Proceeds from issuance of redeemable convertible preferred units, net	57,500
Net cash provided by financing activities	57,500
Subsidiary Issuer
Condensed Financial Statements Captions [Line Items]
Net cash provided by operating activities	197	283
Cash Flows From Investing Activities:
Cash paid for acquisitions and capital expenditures, net of proceeds from divestitures and asset sales	(173)	(283)
Net cash used in investing activities	(173)	(283)
Cash Flows From Financing Activities:
Net borrowings and repayments of debt	(24)
Net cash provided by financing activities	(24)
Guarantor Subsidiaries
Condensed Financial Statements Captions [Line Items]
Net cash provided by operating activities	(21,647)	21,981
Cash Flows From Investing Activities:
Cash paid for acquisitions and capital expenditures, net of proceeds from divestitures and asset sales	(3,216)	(7,691)
Net cash used in investing activities	(3,216)	(7,691)
Cash Flows From Financing Activities:
Payments from (to) affiliates	47,350	(6,891)
Net borrowings and repayments of debt	39,076	3,984
Other financing activities	(17,437)	(2,771)
Net cash provided by financing activities	68,989	(5,678)
Net increase in cash, cash equivalents and restricted cash	44,126	8,612
Cash, cash equivalents and restricted cash—Beginning of period	16,298	4,216
Cash, cash equivalents and restricted cash—End of period	60,424	12,828
Non-Guarantor Subsidiaries
Condensed Financial Statements Captions [Line Items]
Net cash provided by operating activities	28	31
Cash Flows From Investing Activities:
Cash paid for acquisitions and capital expenditures, net of proceeds from divestitures and asset sales	(199)	(485)
Net cash used in investing activities	(199)	(485)
Cash Flows From Financing Activities:
Net borrowings and repayments of debt	(148)
Net cash provided by financing activities	(148)
Net increase in cash, cash equivalents and restricted cash	(319)	(454)
Cash, cash equivalents and restricted cash—Beginning of period	1,849	2,605
Cash, cash equivalents and restricted cash—End of period	1,530	2,151
Eliminations
Condensed Financial Statements Captions [Line Items]
Net cash provided by operating activities	(10,150)	(6,891)
Cash Flows From Investing Activities:
Payments to affiliates	57,500
Net cash used in investing activities	57,500
Cash Flows From Financing Activities:
Payments from (to) affiliates	(47,350)	6,891
Net cash provided by financing activities	$ (47,350)	$ 6,891