Schedule II - Valuation and Qualifying Accounts (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deferred Recovery Cost Reserve [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year		$ 2,557,149	$ 2,557,149
Charged (credited) to expenses
Charged (credited) to other accounts
Deductions		2,557,149
Balance at ending of year			2,557,149
Inventory Reserve [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year	367,558	392,203	479,459
Charged (credited) to expenses	3,774
Charged (credited) to other accounts
Deductions		24,645	87,256
Balance at ending of year	371,332	367,558	392,203
Accounts Receivable Reserve [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year	4,820,593	6,390,593	8,494,672
Charged (credited) to expenses	500,000
Charged (credited) to other accounts
Deductions	189,000	1,570,000	2,104,079
Balance at ending of year	$ 5,131,593	$ 4,820,593	$ 6,390,593