Income Taxes - Income Tax Examination (Details)	3 Months Ended
	Oct. 31, 2017
Minimum [Member] | State and Local Jurisdiction [Member]
Income Tax Examination [Line Items]
Income tax examination, tax years	2006
Minimum [Member] | Foreign Tax Authority [Member]
Income Tax Examination [Line Items]
Income tax examination, tax years	2006
Minimum [Member] | Internal Revenue Service (IRS) [Member]
Income Tax Examination [Line Items]
Income tax examination, tax years	2010
Minimum [Member] | New York City [Member]
Income Tax Examination [Line Items]
Income tax examination, tax years	2011
Minimum [Member] | New York State Division of Taxation and Finance [Member]
Income Tax Examination [Line Items]
Income tax examination, tax years	2012
Maximum [Member] | New York City [Member]
Income Tax Examination [Line Items]
Income tax examination, tax years	2013
Maximum [Member] | New York State Division of Taxation and Finance [Member]
Income Tax Examination [Line Items]
Income tax examination, tax years	2014