Consolidated Statement of Changes in Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Treasury Stock at Cost [Member]	Noncontrolling Interest [Member]	Comprehensive Income [Member]
Balance at Jun. 30, 2009	$ 311,352	$ 7	$ 303,364	$ 4,660	$ (3,644)	$ (4)	$ 6,969	$ (48,525)
Balance (in shares) at Jun. 30, 2009		66,944,000
Warrants exercised	1,287	0	1,287	0	0	0	0
Warrants exercised (in shares)		257,000
UPOs exercised	210	0	210	0	0	0	0
UPOs exercised (in shares)		1,519,000
Share-based compensation	5,712	0	5,712	0	0	0	0
Share-based compensation (in shares)		3,000
Stock option exercises	616	0	616	0	0	0	0
Stock option exercises (in shares)	(98,558,000)	99,000
Stock issuance	34,768	0	34,768	0	0	0	0
Stock issuance (in shares)		5,600,000
Sale of noncontrolling interest	71,409	0	44,397	0	0	0	27,012
Realized gain on available-for-sale securities	(10)	0	0	0	(10)	0	0
Comprehensive income:
Foreign currency translation adjustment	65	0	0	0	64	0	1	65
Pension liability adjustment, net of tax	(851)	0	0	0	(851)	0	0	(851)
Unrealized gain (loss) on available-for-sale securities, net of tax	3	0	0	0	3	0	0	3
Net income	34,268	0	0	34,101	0	0	167	34,268
Total comprehensive income	33,485							33,485
Balance at Jun. 30, 2010	458,829	7	390,354	38,761	(4,438)	(4)	34,149	33,485
Balance (in shares) at Jun. 30, 2010		74,422,000
Share-based compensation	4,332	0	4,332	0	0	0	0
Share-based compensation (in shares)		4,000
Stock option exercises	5,215	1	5,214	0	0	0	0
Stock option exercises (in shares)	(878,025,000)	864,000
Cash dividend declared	(11,269)	0	0	(11,269)	0	0	0
Comprehensive income:
Foreign currency translation adjustment	795	0	0	0	795	0	0	795
Pension liability adjustment, net of tax	647	0	0	0	647	0	0	647
Unrealized gain (loss) on available-for-sale securities, net of tax	1	0	0	0	1	0	0	1
Net income	56,726	0	0	52,808	0	0	3,918	56,726
Total comprehensive income	58,169							58,169
Balance at Jun. 30, 2011	515,276	8	399,900	80,300	(2,995)	(4)	38,067	58,169
Balance (in shares) at Jun. 30, 2011		75,290,000
Share-based compensation	2,482	0	2,482	0	0	0	0
Share-based compensation (in shares)		4,000
Stock option exercises	195	0	195	0	0	0	0
Stock option exercises (in shares)	(38,000,000)	38,000
Cash dividend declared	(15,007)	0	0	(15,007)	0	0	0
Sale of noncontrolling interest	210	0	210	0	0	0	0
Solsil shares purchased	(150)	0	2,888	0	0	0	(3,038)
Acquisition of Quebec Silicon	46,762	0	0	0	0	0	46,762
Comprehensive income:
Foreign currency translation adjustment	319	0	0	0	319	0	0	319
Pension liability adjustment, net of tax	(4,125)	0	0	0	(4,125)	0	0	(4,125)
Unrealized gain (loss) on available-for-sale securities, net of tax	(39)	0	0	0	(39)	0	0	(39)
Net income	57,876	0	0	54,570	0	0	3,306	57,876
Total comprehensive income	54,031							54,031
Balance at Jun. 30, 2012	$ 603,799	$ 8	$ 405,675	$ 119,863	$ (6,840)	$ (4)	$ 85,097	$ 54,031
Balance (in shares) at Jun. 30, 2012		75,332,000