Restructuring Charges (Details) (USD $)	3 Months Ended		9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Restructuring Charges
Restructuring charges	$ 3,886,000	$ 10,748,000	$ 13,672,000	$ 13,378,000
Reconciliation of restructuring liability
Costs charged to expense	3,886,000	10,748,000	13,672,000	13,378,000
Film and Electrolytic
Restructuring Charges
Restructuring charges	1,856,000	10,741,000	8,283,000	12,384,000
Reconciliation of restructuring liability
Costs charged to expense	1,856,000	10,741,000	8,283,000	12,384,000
Tantalum
Restructuring Charges
Restructuring charges	652,000	6,000	2,759,000	905,000
Reconciliation of restructuring liability
Costs charged to expense	652,000	6,000	2,759,000	905,000
Manufacturing relocation costs
Restructuring Charges
Restructuring charges	497,000	261,000	1,658,000	1,646,000
Reconciliation of restructuring liability
Costs charged to expense	497,000	261,000	1,658,000	1,646,000
Costs paid or settled	(497,000)	(261,000)	(1,658,000)	(1,646,000)
Manufacturing relocation costs | China and Mexico
Restructuring Charges
Restructuring charges				1,600,000
Reconciliation of restructuring liability
Costs charged to expense				1,600,000
Manufacturing relocation costs | Bulgaria, China, Macedonia and Mexico
Restructuring Charges
Restructuring charges			1,700,000
Reconciliation of restructuring liability
Costs charged to expense			1,700,000
Personnel reduction costs
Restructuring Charges
Restructuring charges	3,389,000	10,487,000	12,014,000	11,732,000
Workforce reductions and administrative overhead			2,000,000
Reconciliation of restructuring liability
Beginning of period	15,019,000	1,121,000	11,474,000	1,827,000
Costs charged to expense	3,389,000	10,487,000	12,014,000	11,732,000
Costs paid or settled	(4,139,000)	(617,000)	(8,990,000)	(2,521,000)
Change in foreign exchange	239,000	(390,000)	10,000	(437,000)
End of period	14,508,000	10,601,000	14,508,000	10,601,000
Personnel reduction costs | Mexican operations
Restructuring Charges
Restructuring charges			1,500,000
Reconciliation of restructuring liability
Costs charged to expense			1,500,000
Personnel reduction costs | Landsberg, Germany
Restructuring Charges
Restructuring charges			2,800,000
Reconciliation of restructuring liability
Costs charged to expense			2,800,000
Personnel reduction costs | Weymouth, United Kingdom
Restructuring Charges
Restructuring charges			2,300,000
Expected termination benefits/charges			2,600,000
Reconciliation of restructuring liability
Costs charged to expense			2,300,000
Personnel reduction costs | Corporate headquarters
Restructuring Charges
Restructuring charges			2,300,000
Reconciliation of restructuring liability
Costs charged to expense			2,300,000
Personnel reduction costs | Portugal
Restructuring Charges
Restructuring charges			1,100,000
Reconciliation of restructuring liability
Costs charged to expense			1,100,000
Personnel reduction costs | Italy
Restructuring Charges
Restructuring charges				6,100,000
Workforce reductions and administrative overhead				4,500,000
Reconciliation of restructuring liability
Costs charged to expense				6,100,000
Personnel reduction costs | Tantalum | Mexican operations
Restructuring Charges
Restructuring charges				1,200,000
Reconciliation of restructuring liability
Costs charged to expense				$ 1,200,000