Segment and Geographic Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 segment	Sep. 30, 2011	Mar. 31, 2012
Segment and Geographic Information
Number of business groups			3
Segment and geographic information
Net sales	$ 215,991	$ 265,514	$ 439,623	$ 555,370
Operating income (loss)	(14,020)	24,913	(18,065)	65,755
Depreciation and amortization expenses	11,520	11,852	23,177	23,011
Restructuring charges
Total restructuring	8,522	1,605	9,786	2,630
Operating expenses (benefits)
Goodwill impairment	1,092		1,092
Write down of long-lived assets	4,234		4,234
Settlement gain on benefit plan	(1,675)		(1,675)
Assets
Total assets	940,797		940,797		975,552
North and South America ("Americas")
Segment and geographic information
Net sales	62,243	81,663	122,728	154,422
Europe, Middle East, Africa ("EMEA")
Segment and geographic information
Net sales	70,673	106,897	150,058	209,609
Asia and Pacific Rim ("APAC")
Segment and geographic information
Net sales	83,075	76,954	166,837	191,339
Tantalum
Segment and geographic information
Number of manufacturing sites			7
Net sales	109,308	112,290	218,507	234,733
Operating income (loss)	(579)	10,601	1,904	28,013
Depreciation and amortization expenses	6,206	6,705	12,018	12,913
Restructuring charges
Total restructuring	1,987	864	2,031	899
Assets
Total assets	517,782		517,782		511,193
Ceramic
Segment and geographic information
Number of manufacturing sites			2
Net sales	53,116	56,112	104,661	115,491
Operating income (loss)	6,882	10,553	13,479	21,409
Depreciation and amortization expenses	1,864	2,002	3,929	3,805
Restructuring charges
Total restructuring	1,081	49	1,179	88
Assets
Total assets	183,863		183,863		201,971
Film and Electrolytic
Segment and geographic information
Number of manufacturing sites			14
Net sales	53,567	97,112	116,455	205,146
Operating income (loss)	(20,323)	3,759	(33,448)	16,333
Depreciation and amortization expenses	3,450	3,145	7,230	6,293
Restructuring charges
Total restructuring	5,454	692	6,576	1,643
Operating expenses (benefits)
Goodwill impairment			1,092
Write down of long-lived assets			4,234
Settlement gain on benefit plan			(1,700)
Assets
Total assets	$ 239,152		$ 239,152		$ 262,388