Changes in Accumulated Other Comprehensive Income or Loss (Detail) (USD $)	6 Months Ended
	Jun. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at December 31, 2012	$ 1,911,970
Other comprehensive income (loss) before reclassifications	(1,147,117)
Amounts reclassified from accumulated other comprehensive income (loss)
Net current period other comprehensive income (loss)	(1,147,117)
Balance at June 30, 2013	764,853
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at December 31, 2012	14,130
Other comprehensive income (loss) before reclassifications	(6,621)
Amounts reclassified from accumulated other comprehensive income (loss)
Net current period other comprehensive income (loss)	(6,621)
Balance at June 30, 2013	7,509
Accumulated Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at December 31, 2012	1,897,840
Other comprehensive income (loss) before reclassifications	(1,140,496)
Amounts reclassified from accumulated other comprehensive income (loss)
Net current period other comprehensive income (loss)	(1,140,496)
Balance at June 30, 2013	$ 757,344