Fair Value Measurements - Fair Value Hierarchy of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($)	Jun. 30, 2015	Dec. 31, 2014
LIABILITIES:
Contingent consideration	$ 747,000	$ 747,000
Commodity swap contracts	320,190	3,023,271
Level 1 [Member]
LIABILITIES:
Contingent consideration	0	0
Commodity swap contracts	0	0
Level 2 [Member]
LIABILITIES:
Contingent consideration	0	0
Commodity swap contracts	320,190	3,023,271
Level 3 [Member]
LIABILITIES:
Contingent consideration	747,000	747,000
Commodity swap contracts	$ 0	$ 0