Fair Value Measurements (Details 3) (USD $)	12 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2011
Reconciliation of liability measured and recorded at fair value on a recurring basis using Level 3
Beginning balance	$ 2,537,000	$ 775,000
Total net unrealized losses (gains) included in general and administrative expense in earnings	(2,492,000)	(3,083,000)	119,000
Net purchases, issuances, sales and settlements		4,845,000	656,000
Ending balance	45,000	2,537,000	775,000
Byrne Medical Business | Three-year price floor
Reconciliation of liability measured and recorded at fair value on a recurring basis using Level 3
Beginning balance	1,037,000
Total net unrealized losses (gains) included in general and administrative expense in earnings	(992,000)	(1,963,000)
Net purchases, issuances, sales and settlements		3,000,000
Ending balance	45,000	1,037,000
Contingent consideration liability | ConFirm Monitoring Business
Reconciliation of liability measured and recorded at fair value on a recurring basis using Level 3
Beginning balance		775,000
Total net unrealized losses (gains) included in general and administrative expense in earnings		80,000	119,000
Net purchases, issuances, sales and settlements		(855,000)	656,000
Ending balance			775,000
Contingent consideration liability | Byrne Medical Business
Reconciliation of liability measured and recorded at fair value on a recurring basis using Level 3
Beginning balance	1,500,000
Total net unrealized losses (gains) included in general and administrative expense in earnings	(1,500,000)	(1,200,000)
Net purchases, issuances, sales and settlements		2,700,000
Ending balance		$ 1,500,000