Impairment of Real Estate, Impairment of Unconsolidated Entities and Write-Off of Abandoned Development Projects (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jul. 31, 2012
Impairment of real estate
Fair value valuation technique	Indicative Bids
Fair value unobservable input	Indicative Bids
Fair Value Range of Input Values Impairment of Real Estate	N/A(1)
Fair Value, Inputs, Level 3 [Member]
Impairment of real estate
Impairment of real estate	80,929