Stock-Based Compensation (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2011	Oct. 31, 2010	Oct. 31, 2011	Oct. 31, 2010
Amount of stock-based compensation costs and related deferred income tax benefit recognized in the financial statements
Total stock-based compensation costs	$ 3,191	$ 2,337	$ 9,516	$ 11,383
Less amount capitalized into qualifying real estate projects	(1,522)	(519)	(3,446)	(5,104)
Amount charged to operating expenses	1,669	1,818	6,070	6,279
Depreciation expense on capitalized stock-based compensation	693	150	1,064	451
Total stock based compensation expense	2,362	1,968	7,134	6,730
Deferred income tax benefit	829	660	2,567	2,301
Employee Stock Option [Member]
Amount of stock-based compensation costs and related deferred income tax benefit recognized in the financial statements
Total stock-based compensation costs	806	479	1,801	4,693
Restricted Stock [Member]
Amount of stock-based compensation costs and related deferred income tax benefit recognized in the financial statements
Total stock-based compensation costs	$ 2,385	$ 1,858	$ 7,715	$ 6,690