Debt - Senior Credit Agreement (Details)		12 Months Ended
	Sep. 15, 2015 USD ($)	Jan. 26, 2019 USD ($)	Jan. 25, 2020 USD ($)	Oct. 19, 2018 USD ($)
Line of Credit Facility [Line Items]
Letters of credit outstanding amount		$ 48,600,000	$ 52,300,000
Line of Credit Facility, Remaining Borrowing Capacity		412,900,000	287,000,000.0
Incremental Facility, Minimum
Line of Credit Facility [Line Items]
Debt instrument, face amount	$ 350,000,000.0
Standby Letters of Credit
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				$ 200,000,000.0
Letters of credit outstanding amount			48,600,000
0.75% Convertible Senior Notes Due 2021
Line of Credit Facility [Line Items]
Debt instrument, face amount	$ 485,000,000.0	$ 485,000,000	$ 460,000,000.0
Debt, interest rate (in percent)		0.75%	0.75%
Outstanding Debt Credit Agreement Threshold			$ 250,000,000.0
Credit Agreement Liquidity Requirement			150,000,000.0
Minimum
Line of Credit Facility [Line Items]
Debt Instrument, Covenant Compliance, Consolidated Leverage Ratio		3.50
Debt Instrument, Covenant Compliance, Consolidated Interest Coverage Ratio		3.00
Maximum
Line of Credit Facility [Line Items]
Debt Instrument, Covenant Compliance, Consolidated Leverage Ratio		1.00
Debt Instrument, Covenant Compliance, Consolidated Interest Coverage Ratio		1.00
Credit Agreement - Term Loan (matures April 2020)
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				450,000,000.0
Unrestricted Cash and Cash Equivalents Credit Agreement Threshold			$ 50,000,000.0
Debt Instrument, Covenant Compliance, Consolidated Leverage Ratio	2.25
Credit Agreement - Revolving facility (matures April 2020)
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 450,000,000.0			$ 750,000,000.0