Discounted Operation - Schedule Of Changes in Company's Estimated Liability (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jan. 31, 2014
Schedule of Changes in Company's Estimated Liability [Abstract]
Additional liability	$ 1,700
Straight Path [Member]
Schedule of Changes in Company's Estimated Liability [Abstract]
Balance, beginning of period	931
Additional liability	1,700
Payments	(262)
Balance, end of period	$ 2,369