Goodwill and Other Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2010
Goodwill [Roll Forward]
Goodwill	$ 111,159	$ 109,681
Accumulated impairment loss	(57,656)	(57,656)
Quebec Silicon acquisition	3,063
Balance at beginning of period	53,503	52,025
Core Metals purchase price allocation adjustments		1,124
Foreign exchange rate changes	174	354
Goodwill	114,396	111,159	109,681
Accumulated impairment loss	(57,656)	(57,656)	(57,656)
Balance at end of period	56,740	53,503	52,025
Finite-Lived Intangible Assets [Line Items]
Amortization expense	0	0	310
Finite-Lived Intangible Assets, Net, Ending Balance	0	0
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	477	477
GMI [Member]
Goodwill [Roll Forward]
Goodwill	31,529	30,405
Accumulated impairment loss	0	0
Quebec Silicon acquisition	3,063
Balance at beginning of period	31,529	30,405
Core Metals purchase price allocation adjustments		1,124
Foreign exchange rate changes	(1)	0
Goodwill	34,591	31,529
Accumulated impairment loss	0	0
Balance at end of period	34,591	31,529
Globe Metales [Member]
Goodwill [Roll Forward]
Goodwill	14,313	14,313
Accumulated impairment loss	0	0
Quebec Silicon acquisition	0
Balance at beginning of period	14,313	14,313
Core Metals purchase price allocation adjustments		0
Foreign exchange rate changes	0	0
Goodwill	14,313	14,313
Accumulated impairment loss	0	0
Balance at end of period	14,313	14,313
Solsil [Member]
Goodwill [Roll Forward]
Goodwill	57,656	57,656
Accumulated impairment loss	(57,656)	(57,656)
Quebec Silicon acquisition	0
Balance at beginning of period	0	0
Core Metals purchase price allocation adjustments		0
Foreign exchange rate changes	0	0
Goodwill	57,656	57,656
Accumulated impairment loss	(57,656)	(57,656)
Balance at end of period	0	0
Other [Member]
Goodwill [Roll Forward]
Goodwill	7,661	7,307
Accumulated impairment loss	0	0
Quebec Silicon acquisition	0
Balance at beginning of period	7,661	7,307
Core Metals purchase price allocation adjustments		0
Foreign exchange rate changes	175	354
Goodwill	7,836	7,661
Accumulated impairment loss	0	0
Balance at end of period	$ 7,836	$ 7,661