Goodwill and Other Intangibles - Intangible Assets Subject to Amortization (Detail) $ in Thousands	Jun. 30, 2018 USD ($)
Finite Lived Intangible Assets [Line Items]
Gross Amount	$ 559,870
Accumulated Amortization	(75,271)
Net Balance	484,599
Noncompetition agreements
Finite Lived Intangible Assets [Line Items]
Gross Amount	6,274
Accumulated Amortization	(6,162)
Net Balance	112
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Gross Amount	65,348
Accumulated Amortization	(19,480)
Net Balance	45,868
Operating Permits
Finite Lived Intangible Assets [Line Items]
Gross Amount	458,952
Accumulated Amortization	(29,790)
Net Balance	429,162
Use Rights And Other
Finite Lived Intangible Assets [Line Items]
Gross Amount	16,496
Accumulated Amortization	(10,763)
Net Balance	5,733
Trade names
Finite Lived Intangible Assets [Line Items]
Gross Amount	12,800
Accumulated Amortization	(9,076)
Net Balance	$ 3,724