Debt Securities Outstanding (Detail) (USD $) In Millions, unless otherwise specified	Aug. 02, 2014
Schedule of Available-for-sale Securities [Line Items]
Less than one year, cost	$ 1.8
Year two through year five, cost	11.1
Year six through year ten, cost	7.0
After ten years, cost	0.1
Debt securities outstanding, cost	20.0
Less than one year, fair value	1.8
Year two through year five, fair value	11.0
Year six through year ten, fair value	6.9
After ten years, fair value	0.1
Debt securities outstanding, fair value	$ 19.8