Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) (Unaudited) (USD $)	3 Months Ended		6 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2013	Jul. 31, 2012
Statement of Comprehensive Income [Abstract]
Tax amount related to unrealized net gains on investment securities	$ (111,000)	$ (9,000)	$ (195,000)	$ (7,000)
Tax amount related to foreign currency translation adjustments	0	(534,000)	100,000	(623,000)
Tax amount related to unrealized net gains (losses) on interest rate derivative contracts	$ (10,510,000)	$ 2,306,000	$ (10,776,000)	$ (1,480,000)