Segments - Long-lived assets by major geographic area (Details) - USD ($) $ in Thousands	Jul. 31, 2018	Jul. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 1,392,306	$ 813,909
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	878,415	$ 813,909
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 513,891