Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Goodwill acquired on acquisition	$ 37,900,000	$ 41,774,000
Non-cash impairment charges	60,939,000	108,184,000	$ 15,934,000
Unproved leasehold interests
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Goodwill acquired on acquisition	37,900,000	37,900,000
Water Resources Company
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Goodwill acquired on acquisition	0	$ 3,874,000
Water Resources Company | Groundwater Leases
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Identified intangible assets	1,681,000
Texas | Water Resources Company
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Non-cash impairment charges	$ 3,874,000