Equity Method Investments - Summarized Financial Information (Details) - NEC TOKIN Corporation - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Balance Sheet Related Disclosures [Abstract]
Current assets continuing operations		$ 204,654
Assets held for sale (current)		118,983
Noncurrent assets continuing operations		285,952
Current liabilities continuing operations		375,433
Liabilities held for sale (current)		50,008
Noncurrent liabilities continuing operations		65,657
Income Statement Related Disclosures [Abstract]
Net sales	$ 23,649	328,822	$ 301,898
Gross profit	6,647	74,465	67,409
Net income (loss)	$ 247,786	$ 128,502	$ (42,995)