Share capital and additional paid-in capital (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2012
Options Redemption Price	$ 0.01
Class B Common Stock [Member]
Options Exercise Price	$ 50
Common Stock, Capital Shares Reserved for Future Issuance	145,000
Grant Of Options To Common Stock Share Holders and Preferred Stock Share Holders	1/100 of a share
Criteria One Description	if a person or group acquires or commences a tender offer for 20% or more of the Company's common shares.
Criteria Two Description	Option holders (other than the acquiring person or group) will also be entitled to buy, for the $37.50 exercise price, common shares with a then market value of $100.00 in the event a person or group actually acquires 20% or more of the Company's common shares.
Option Expiration Date	Jul. 31, 2017