Marketable Securities - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Available-for-sale securities	$ 421,875	$ 0	$ 0
Unrealized gains or losses reclassified from other comprehensive income	119,720	0	0
Marketable Securities, Realized Gain (Loss)	183,371	0	0
Gross realized gains or losses		0	0
Common Stock [Member]
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Available-for-sale securities	500,000
Unrealized gains or losses reclassified from other comprehensive income	100,000
Marketable Securities, Realized Gain (Loss)	$ 200,000