Other liabilities (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended		110 Months Ended		6 Months Ended		1 Months Ended	6 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2013	May 31, 2012	May 31, 2013	Nov. 30, 2012	May 31, 2013 Approximations [Member]	May 31, 2013 Number of RSU's [Member]	Jun. 30, 2013 Officers [Member]	May 31, 2013 Officers [Member] Number of RSU's [Member]
Units granted								1,000,000		1,000,000
Stock-based compensation	$ 2,000,000	$ 5,494,000	$ 6,113,000	$ 5,494,000	$ 16,637,000		$ 1,000,000
Deferred Compensation Share-based Arrangements, Liability, Current							900,000
Deferred Compensation Share-based Arrangements, Liability, Classified, Noncurrent	148,000		148,000		148,000	0	100,000
Units vested									333,333
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures									150,000
Payments for Settlement of Units Vested									$ 300,000