Income Taxes (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended
	Jul. 31, 2013	Jul. 31, 2012		Jul. 31, 2013	Jul. 31, 2012
Income Tax Disclosure [Abstract]
Effective tax rate	36.10%	30.00%		40.00%	29.60%
Decrease in income tax provision	49.90%			45.50%
Provision for income taxes	$ 8,291	$ 16,550	[1]	$ 21,628	$ 39,692	[1]
Effective tax rate reconciliation, percentage				35.00%

[1] See Note 2 - Restatement of Consolidated Financial Statements.