Investment in NEC TOKIN (Details) (NEC TOKIN, USD $)	3 Months Ended							3 Months Ended
	Jun. 30, 2013	Feb. 01, 2013 Stockholders' Agreement item	Jun. 30, 2013 Put Option	Feb. 01, 2013 KEC	Feb. 01, 2013 KEC Stock Purchase Agreement	Mar. 12, 2012 KEC Stock Purchase Agreement	Feb. 01, 2013 KEC Stockholders' Agreement item	Jun. 30, 2013 KEC Option Agreement item	Mar. 31, 2013 KEC Option Agreement	Jun. 30, 2013 KEC Put Option item
Investment in NEC TOKIN
Common stock acquired (as a percent)						51.00%
Economic ownership to be acquired (as a percent)						34.00%		49.00%
Purchase price				$ 54,500,000
Purchase price paid					50,000,000
Number of director positions		7					4
Purchase price for expected additional shares that may be acquired									50,000,000
Ownership interest maintained after acquisition of additional shares (as a percent)								51.00%
LTM EBITDA multiple								6		6
Value of net call derivative options			500,000
Transaction expenses				4,500,000
Summarized financial information
Current assets	209,185,000
Noncurrent assets	391,632,000
Current liabilities	106,023,000
Noncurrent liabilities	398,739,000
Sales	123,192,000
Gross profit	18,300,000
Net loss	(8,729,000)
Excess of the carrying value for its investment over equity in memo accounts	$ 16,100,000