Income Taxes - Income Tax Examination (Details)	3 Months Ended
	Apr. 30, 2018
Minimum [Member] | State and Local Jurisdiction [Member]
Income Tax Examination [Line Items]
Open Tax Year	2006
Minimum [Member] | Foreign Tax Authority [Member]
Income Tax Examination [Line Items]
Open Tax Year	2006
Minimum [Member] | Internal Revenue Service [Member]
Income Tax Examination [Line Items]
Open Tax Year	2010
Minimum [Member] | New York City [Member]
Income Tax Examination [Line Items]
Income Tax Examination, Year under Examination	2011
Minimum [Member] | New York State Division of Taxation and Finance [Member]
Income Tax Examination [Line Items]
Income Tax Examination, Year under Examination	2012
Maximum [Member] | New York City [Member]
Income Tax Examination [Line Items]
Income Tax Examination, Year under Examination	2013
Maximum [Member] | New York State Division of Taxation and Finance [Member]
Income Tax Examination [Line Items]
Income Tax Examination, Year under Examination	2014