Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)		6 Months Ended
	Jan. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	$ 3,000,000
Additional impairment charges		$ 0
Aggregate amortization expense		$ 716,000,000	$ 779,000,000
Equipment Leasing [Member]
Finite-Lived Intangible Assets [Line Items]
Impairment of intangible assets	$ 600,000
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life of intangible assets		15 years
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life of intangible assets		5 years