Acquisitions - Narrative (Details) - USD ($)			1 Months Ended		3 Months Ended	12 Months Ended
	Mar. 04, 2015	Jan. 13, 2015	Sep. 30, 2015	Mar. 31, 2015	Jul. 31, 2016	Jan. 29, 2017	Jan. 31, 2016	Jan. 25, 2015
Fair value of earn-out liability						$ 1,242,000	$ 1,457,000
Borrowings under line of credit				$ 35,000,000		97,000,000	0	$ 0
Goodwill						329,703,000	329,703,000
Triune Systems
Effective date of acquisition	Mar. 04, 2015
Name of acquired entity	Triune Systems, L.L.C.
Purchase price	$ 45,000,000
Cash paid to acquire business	35,000,000		$ 9,500,000		$ 500,000
Remaining cash consideration to be paid	10,000,000
Fair value of earn-out liability						0	$ 0
Goodwill expected to be deductible for tax purposes						$ 16,100,000
Earn-out liability	16,200,000
Acquisition consideration allocated to finite-lived intangile assets	12,000,000
EnVerv
Effective date of acquisition		Jan. 13, 2015
Name of acquired entity		EnVerv, Inc.
Purchase price		$ 4,900,000
Goodwill								3,400,000
Core technologies | EnVerv
Acquisition consideration allocated to finite-lived intangile assets								$ 1,400,000
Earn-out Payable Within First Three Fiscal Years Of Acquisition Date [Member] | Triune Systems
Potential payments under earn-out arrangements, high estimate	$ 70,000,000
Period over which contingent consideration will be paid	3 years
Additional Earn-out Payable After Third Fiscal Year From Acquisition Date [Member] | Triune Systems
Potential payments under earn-out arrangements, high estimate	$ 16,000,000