Prepaid and Other Current and Non-current Assets - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2017 option
Operating Leased Assets [Line Items]
Term of lease (in years)	4 years
Term of lease extension (in years)	20 years
Term of lease renewals (in years)	5 years
Number of renewal options for operating leases	6
Texas
Operating Leased Assets [Line Items]
Term of lease (in years)	10 years
Maximum
Operating Leased Assets [Line Items]
Term of lease (in years)	60 years