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Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended							3 Months Ended		6 Months Ended
	Aug. 31, 2018	May 30, 2018	Mar. 31, 2018	Nov. 30, 2017	Aug. 31, 2017	May 31, 2017	Feb. 28, 2017	Aug. 04, 2018	Jul. 29, 2017	Aug. 04, 2018	Jul. 29, 2017	Feb. 04, 2018
Summary of Significant Accounting Policies [Line Items]
Cash dividends declared per share (in dollars per share)		$ 0.225	$ 0.225	$ 0.160	$ 0.160	$ 0.160	$ 0.160	$ 0.225	$ 0.160	$ 0.450	$ 0.320
Operating leases, future minimum payments due								$ 3,800.0		$ 3,800.0
Property, Plant and Equipment
Summary of Significant Accounting Policies [Line Items]
Property and equipment purchased but not yet paid										$ 10.0	$ 6.5
Subsequent Event
Summary of Significant Accounting Policies [Line Items]
Cash dividends declared per share (in dollars per share)	$ 0.225
Retained Earnings \| Accounting Standards Update 2014-09
Summary of Significant Accounting Policies [Line Items]
Cumulative-effect adjustment												$ 20.0