Commitments and Contingencies - Additional Information (Detail)	May. 31, 2015 USD ($) Lawsuits	Dec. 31, 2014 Lawsuits
Commitments and Contingencies Disclosure [Line Items]
Number of lawsuits	92
Insurance coverage subject to deductible limit | $	$ 250,000
Delaware Cases
Commitments and Contingencies Disclosure [Line Items]
Number of lawsuits		2
Washington Case
Commitments and Contingencies Disclosure [Line Items]
Number of lawsuits		1
Quest Integrity
Commitments and Contingencies Disclosure [Line Items]
Number of lawsuits		3