Other Noncurrent Assets - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Other Assets Non Current [Line Items]
Indefinite-lived intangible asset		$ 5.1
Contract related intangible asset impairment	$ 5.1
Real Estate Management And Development
Other Assets Non Current [Line Items]
Contract related intangible asset impairment	$ 5.1
Real Estate Management And Development | City Of Henderson
Other Assets Non Current [Line Items]
Delivery contract extended period	25 years
Water delivery contract revenue, percentage	70.00%
Real Estate Management And Development | Customer Relationships
Other Assets Non Current [Line Items]
Indefinite-lived intangible asset	$ 5.1
Contract related intangible asset impairment	$ 5.1