Shareholders' Equity - Stock Purchase from NBCU (Details) - USD ($) $ / shares in Units, $ in Thousands		6 Months Ended
	Jan. 31, 2017	Jul. 29, 2017	Jan. 28, 2017
Class of Stock [Line Items]
Common stock repurchased from NBCU, Value		$ 5,055
Common stock, shares owned by related party		65,220,233	65,192,314
NBCU [Member]
Class of Stock [Line Items]
Common stock repurchased from NBCU, Shares	4,400,000
Common stock repurchased from NBCU, Value	$ 5,000
Sale of stock, price per share	$ 1.12
Common stock, shares owned by related party	2,741,849	2,741,849
Percentage of ownership in Company after transaction	4.50%