Financial instruments (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Recurring
Cash equivalents	$ 0	$ 16,177,462
Restricted cash	0	7,500,000
Marketable securities	8,570,338	8,496,372
Total Recurring	8,570,338	32,173,834
Nonrecurring
Investment in affiliate	6,925,346	6,634,598
Fair Value, Inputs, Level 1 [Member]
Recurring
Cash equivalents	0	16,177,462
Restricted cash	0	7,500,000
Marketable securities	8,570,338	8,496,372
Total Recurring	8,570,338	32,173,834
Nonrecurring
Investment in affiliate	0	0
Fair Value, Inputs, Level 2 [Member]
Recurring
Cash equivalents	0	0
Restricted cash	0	0
Marketable securities	0	0
Total Recurring	0	0
Nonrecurring
Investment in affiliate	0	0
Fair Value, Inputs, Level 3 [Member]
Recurring
Cash equivalents	0	0
Restricted cash	0	0
Marketable securities	0	0
Total Recurring	0	0
Nonrecurring
Investment in affiliate	$ 6,925,346	$ 6,634,598

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Trading Securities which consist of all investments in certain debt and equity securities that are bought and held principally for the purpose of selling them in the near term (thus held for only a short period of time) or for which an entity has elected the fair value option. Trading generally reflects active and frequent buying and selling, and trading securities are generally used with the objective of generating profits on short-term differences in price, but this category of investments may also include items which are not intended to be sold in the near term or for which the fair value option has been elected.

+ References+ Details