Acquisitions - Narrative (Details) - USD ($)			1 Months Ended		3 Months Ended	12 Months Ended
	Jul. 01, 2017	Mar. 04, 2015	Sep. 30, 2015	Mar. 31, 2015	Jul. 31, 2016	Jan. 28, 2018	Jan. 29, 2017	Jan. 31, 2016
Fair value of earn-out liability						$ 21,668,000	$ 1,242,000
Borrowings under line of credit				$ 35,000,000		0	97,000,000	$ 0
Goodwill						341,897,000	329,703,000
AptoVision
Effective date of acquisition	Jul. 01, 2017
Name of acquired entity	AptoVision Technologies Inc.
Cash paid to acquire business	$ 17,600,000
Fair value of earn-out liability						21,000,000	$ 0
Earn-out liability	21,000,000
Goodwill	12,194,000					12,194,000
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
Goodwill expected to be deductible for tax purposes						$ 16,100,000
Earn-out liability		16,200,000
Earn-out Payable Within First Three Fiscal Years Of Acquisition Date [Member] | AptoVision
Potential payments under earn-out arrangements, high estimate	$ 47,000,000
Period over which contingent consideration will be paid	3 years
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
Accrued liabilities | AptoVision
Earn-out liability	$ 8,900,000
Other long-term liabilities | AptoVision
Earn-out liability	12,100,000
Selling, general and administrative expenses | AptoVision
Acquisition related transaction costs	$ 1,600,000