Segment Information (Schedule of Segment Perfomance Measures by Segment) (Detail) - USD ($) $ in Thousands	3 Months Ended											12 Months Ended
	Jun. 30, 2016	[1]	Mar. 31, 2016	[2]	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	[3]	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Net sales	$ 135,424		$ 157,926		$ 131,674	$ 133,500	$ 146,587		$ 145,796	$ 123,765	$ 130,803	$ 558,524	$ 546,951	$ 510,179
Gross profit	$ 34,047		$ 38,289		$ 35,868	$ 34,581	$ 41,166		$ 36,598	$ 30,019	$ 27,651	142,785	135,434	114,703
Income before income taxes												53,854	53,865	44,674
Operating Segments | Human Health
Segment Reporting Information [Line Items]
Net sales												228,035	225,263	160,217
Gross profit												77,880	75,749	48,496
Income before income taxes												36,362	35,152	19,710
Operating Segments | Pharmaceutical Ingredients
Segment Reporting Information [Line Items]
Net sales												161,011	149,296	176,425
Gross profit												28,752	26,683	36,615
Income before income taxes												11,856	8,697	17,557
Operating Segments | Performance Chemicals
Segment Reporting Information [Line Items]
Net sales												169,478	172,392	173,537
Gross profit												36,153	33,002	29,592
Income before income taxes												17,799	14,289	13,273
Unallocated Corporate
Segment Reporting Information [Line Items]
Net sales
Gross profit
Income before income taxes												$ (12,163)	$ (4,273)	$ (5,866)

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

[2] 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.

[3] Includes pretax items consisting of $1,618 environmental remediation charge in connection with Arsynco, $3,468 reversal of contingent consideration related to the PACK acquisition and $3,497 change in estimate for product returns.