Reportable Segment Information (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016	Jul. 31, 2016
Product revenue:
Product Revenue		$ 130,330	$ 125,938	$ 250,582	$ 240,067
Engineering revenue:
Engineering Revenue		1,204	1,931	2,077	2,750
Net revenue:
Total net revenue		131,534	127,869	252,659	242,817
Income from operations:
Income (loss) from operations		9,450	1,509	13,408	3,497
Total other income (loss), net		30	(3,500)	(400)	(4,000)
Income (loss) before income taxes		9,478	(1,998)	12,994	(468)
Identifiable total assets by segment:
Assets		628,443		628,443		$ 632,897
Asset impairment charges		10,423		10,423
Total Identifiable Assets
Identifiable total assets by segment:
Assets		564,300	559,000	564,300	559,000
Reportable segments
Identifiable total assets by segment:
Assets		365,400	393,400	365,400	393,400
Corporate
Identifiable total assets by segment:
Identifiable assets (excluding goodwill)	[1]	198,900	165,600	198,900	165,600
Medical Imaging
Product revenue:
Product Revenue		71,200	72,400	137,700	136,800
Engineering revenue:
Engineering Revenue		1,200	1,100	1,900	1,700
Net revenue:
Total net revenue		72,400	73,500	139,600	138,500
Income from operations:
Income (loss) from operations	[2]	12,200	11,600	18,900	18,000
Medical Imaging | Reportable segments
Identifiable total assets by segment:
Assets		179,900	191,100	179,900	191,100
Ultrasound
Product revenue:
Product Revenue		40,300	42,600	75,900	79,100
Engineering revenue:
Engineering Revenue			700	200	900
Net revenue:
Total net revenue		40,300	43,300	76,100	80,000
Income from operations:
Income (loss) from operations	[3]	(4,500)	(9,900)	(10,300)	(14,500)
Ultrasound | Reportable segments
Identifiable total assets by segment:
Assets		142,200	152,500	142,200	152,500
Security and Detection
Product revenue:
Product Revenue		18,800	10,900	37,000	24,200
Engineering revenue:
Engineering Revenue			200		200
Net revenue:
Total net revenue		18,800	11,100	37,000	24,400
Income from operations:
Income (loss) from operations	[4]	1,800	(200)	4,800
Security and Detection | Reportable segments
Identifiable total assets by segment:
Assets		43,300	$ 49,800	43,300	$ 49,800
Pathfinder Therapeutics Inc
Identifiable total assets by segment:
Asset impairment charges		$ 600		$ 600

[1] Includes cash and cash equivalents of $139.9 million and $97.3 million as of January 31, 2017 and July 31, 2016, respectively.

[2] Includes restructuring charges of $0.09 million and $1.9 million for three months ended January 31, 2017 and January 31, 2016, respectively and $0.11 million and $4.0 million for six months January 31, 2017 and January 31, 2016.

[3] Includes restructuring charges of $0.17 million and $0.6 million for three months ended January 31, 2017 and January 31, 2016, respectively and $0.18 million and $1.3 million for six months January 31, 2017 and January 31, 2016. Includes contingent consideration charges of $(8.2) million and $(8.1) million related to Oncura for three and six months ended January 31, 2017, respectively, asset impairment charges of $9.8 million related to Oncura for three and six months ended January 31, 2017, charges for the BK Medical matter of $10.1 million for three and six months ended January 31, 2016.

[4] Includes restructuring charges of $0.01 million and $0.6 million for three months ended January 31, 2017 and January 31, 2016, respectively and $0.01 million and $1.2 million for six months January 31, 2017 and January 31, 2016. Includes asset impairment charges of $0.6 million related to Pathfinder for three and six months ended January 31, 2017.