Commitments and Contingencies (Tables)

3 Months Ended

Mar. 31, 2013

Commitments and Contingencies Disclosure [Abstract]

Schedule of product warranty activity

	March 31, 2013		March 31, 2012
Beginning balance - January 1	$	2,671,409	$	1,210,909
Additions for current period deliveries	167,362		144,879
Warranty costs incurred during the period	(965,878)		(264,641)
Ending balance - March 31	$	1,872,893	$	1,091,147