Land held for divestiture (Details Textuals) (USD $)	3 Months Ended		9 Months Ended			9 Months Ended	3 Months Ended			9 Months Ended
	Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2013	Oct. 31, 2012	Jan. 31, 2013	Oct. 31, 2013 North Carolina land [Member] acre	Oct. 31, 2012 Bulk sale [Member]	Jul. 31, 2012 Prosper, Texas land project [Member]	Jul. 31, 2012 Central Station [Member]	Oct. 31, 2012 Central Station [Member]	Oct. 31, 2012 Mesa del Sol [Member]	Jul. 31, 2012 Mesa del Sol [Member] acre
Land held for divestiture [Line Items]
Carrying value of land held for divestiture	$ 1,990,000		$ 1,990,000		$ 2,706,000
Area of land parcel sold (in acres)						1,000
Estimated fair value of the underlying collateral						4,100,000
Bad debt expense	0	0	9,000,000	0		9,000,000
Bad debt expense, net of noncontrolling interest						8,300,000
Bad debt expense, after tax						4,980,000
Number of land projects							6
Sales price of land							22,245,000	29,800,000
Gain (loss) on sale of land held for divestiture							(2,100,000)	7,600,000
Gain on extinguishment of debt of land held for divestiture	0	2,227,000	0	2,227,000			2,227,000
Ownership percentage of land project								51.00%
Gain on sale of land net of noncontrolling interest								3,900,000
Impairment of land held for divestiture	0	0	0	15,796,000						17,000,000	15,000,000
Unsolicited offer to purchase ownership interest in remaining land parcels									$ 30,000,000
Area of land held for divestiture (in acres)												3,000