Segment and Geographic Data - Information by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 29, 2017	Jan. 28, 2017	Oct. 29, 2016	Jul. 30, 2016	Apr. 30, 2016	Jan. 30, 2016	Oct. 31, 2015	Aug. 01, 2015	Apr. 29, 2017	Apr. 30, 2016	Apr. 25, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 1,445,032	$ 1,397,418	$ 1,418,241	$ 1,332,436	$ 1,453,770	$ 1,400,853	$ 1,389,210	$ 1,142,870	$ 5,593,127	$ 5,386,703	$ 3,910,865
Property and equipment, net	298,452				293,315				298,452	293,315
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									4,725,322	4,457,254	3,029,541
Property and equipment, net	286,178				278,667				286,178	278,667
United Kingdom [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									547,968	626,603	649,541
Property and equipment, net	1,947				2,459				1,947	2,459
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									319,837	302,846	$ 231,783
Property and equipment, net	$ 10,327				$ 12,189				$ 10,327	$ 12,189