Segment Information (Schedule of Segment Perfomance Measures by Segment) (Detail) - USD ($) $ in Thousands	3 Months Ended														12 Months Ended
	Jun. 30, 2017	[1],[2]	Mar. 31, 2017	[2],[3]	Dec. 31, 2016	[2]	Sep. 30, 2016	[4]	Jun. 30, 2016	[5]	Mar. 31, 2016	[6]	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Net sales	$ 194,620		$ 190,128		$ 125,552		$ 128,018		$ 135,424		$ 157,926		$ 131,674	$ 133,500	$ 638,318	$ 558,524	$ 546,951
Gross profit	$ 36,829		$ 42,319		$ 30,805		$ 30,839		$ 34,047		$ 38,289		$ 35,868	$ 34,581	140,792	142,785	135,434
Income before income taxes															17,361	53,854	53,865
Operating Segments | Human Health
Segment Reporting Information [Line Items]
Net sales															315,395	228,035	225,263
Gross profit															78,109	77,880	75,749
Income before income taxes															15,434	36,362	35,152
Operating Segments | Pharmaceutical Ingredients
Segment Reporting Information [Line Items]
Net sales															157,445	161,011	149,296
Gross profit															25,474	28,752	26,683
Income before income taxes															9,322	11,856	8,697
Operating Segments | Performance Chemicals
Segment Reporting Information [Line Items]
Net sales															165,478	169,478	172,392
Gross profit															37,209	36,153	33,002
Income before income taxes															18,829	17,799	14,289
Unallocated Corporate
Segment Reporting Information [Line Items]
Net sales
Gross profit
Income before income taxes															$ (26,224)	$ (12,163)	$ (4,273)

[1] Includes pretax item of $3,139 representing immaterial correction of an error associated with certain accrued expenses.

[2] Results for the last nine days of the quarter ended December 31, 2016 and for the subsequent two quarters reflect the acquisition of certain generic products and related assets from Citron and Lucid on December 21, 2016.

[3] Includes pretax item of $733 environmental remediation charge in connection with Arsynco.

[4] Includes pretax item of $170 environmental remediation charge in connection with Arsynco.

[5] Includes pretax item of $1,313 environmental remediation charge in connection with Arsynco.

[6] Includes pretax items consisting of $833 reversal of contingent consideration related to the PACK acquisition and $241 reversal of contingent consideration related to the acquisition of a company in France.