Operating Segments, External customers by products and services (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Sep. 30, 2013 Segment	Sep. 30, 2012
Operating Segments [Abstract]
Number of reportable segments	5
Revenue from External Customer by Product Line [Abstract]
Net sales	$ 172,994	$ 200,708
Silicon Metal [Member]
Revenue from External Customer by Product Line [Abstract]
Net sales	85,335	112,912
Silicon-based Alloys [Member]
Revenue from External Customer by Product Line [Abstract]
Net sales	61,396	67,141
Other [Member]
Revenue from External Customer by Product Line [Abstract]
Net sales	$ 26,263	$ 20,655