Environmental Obligations - Additional Information (Detail) - USD ($)	1 Months Ended	9 Months Ended
	Jul. 31, 2012	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Other Commitments [Line Items]
Pollution legal liability insurance policy duration	10 years
Pollution legal liability insurance policy aggregate limit	$ 50,000,000
Remediation agreement of lease		We have agreed to be responsible for environmental contamination at the premises that was known at the time the lease commenced, and which existed prior to commencement of the lease and is discovered (other than as a result of a voluntary site investigation) during the first ten years of the lease term (or a shorter period for a minority of such leases).
Environmental remediation obligations		$ 64,862,000		$ 74,516,000
Accretion expense		2,621,000	$ 3,020,000
Amounts of credits to environmental expenses included in continuing and discontinued operations		6,116,000	3,804,000
Increase in carrying value of property		$ 3,560,000	5,384,000
Estimated remaining useful life of underground storage tank for capitalized asset retirement costs		10 years
Depreciation and amortization expense for capitalized asset retirement costs		$ 3,281,000	3,934,000
Capitalized asset retirement costs		45,982,000		49,125,000
Non-cash impairment charges		$ 4,986,000	$ 6,232,000
Minimum [Member]
Other Commitments [Line Items]
Environmental remediation liability discount range		4.00%
Environmental remediation liability fair value, expected future net cash flows		2.00%
Maximum [Member]
Other Commitments [Line Items]
Environmental remediation liability discount range		7.00%
Environmental remediation liability fair value, expected future net cash flows		2.75%
Reasonably Estimable Environmental Remediation Obligation [Member]
Other Commitments [Line Items]
Environmental remediation liability		$ 20,199,000		29,507,000
Known Environmental Liabilities [Member]
Other Commitments [Line Items]
Capitalized asset retirement costs		18,964,000		20,636,000
Future Environmental Liabilities for Preexisting Unknown Contamination [Member]
Other Commitments [Line Items]
Capitalized asset retirement costs		$ 27,018,000		$ 28,489,000