Income Taxes Income Taxes - Additional Information (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Income Taxes
Deferred tax assets unrecognized tax benefits	$ 38,893	$ 32,794
Undistributed earnings of foreign subsidiaries	432,481
Possible change in unrecognized tax benefit, lower	0
Possible change in unrecognized tax benefit, upper	4,000
Income tax penalties and interest expense	(1,710)	(297)	(677)
Income tax penalties and interest accrued	7,687	9,538
Unrecognized tax benefits that would impact effective tax rate	$ 18,674
Domestic Tax Authority
Income Taxes
Open tax year	2011
Ireland
Income Taxes
Open tax year	2010