Supplemental Balance Sheets and Statements of Operations Detail (Tables)

12 Months Ended

Mar. 31, 2018

Disclosure Text Block Supplement [Abstract]

Schedule of accounts receivable

	March 31,
(amounts in thousands)	2018			2017
Accounts receivable:
Trade	$	166,459		$	112,940
Allowance for doubtful accounts reserve	(1,210		)	(942		)
Ship-from-stock and debit reserve ("SFSD")	(17,362		)	(15,489		)
Returns reserves	(2,616		)	(2,913		)
Rebates reserves	(446		)	(564		)
Price protection reserves	(420		)	(506		)
Other	(329		)	—
Accounts receivable, net	$	144,076		$	92,526

Schedule of activity in allowances for accounts receivables

The following table presents the annual activities included in the allowance for these commitments (amounts in thousands):

Balance at March 31, 2015	$	24,647
Reduction in sales	93,850
Actual adjustments applied	(95,596		)
Other	77
Balance at March 31, 2016	22,978
Reduction in sales	87,739
Actual adjustments applied	(90,365		)
Other	62
Balance at March 31, 2017	20,414
Reduction in sales	94,660
Actual adjustments applied	(92,959		)
Other	268
Balance at March 31, 2018	$	22,383

Schedule of components of inventories

	March 31,
(amounts in thousands)	2018			2017
Inventories:
Raw materials and supplies	$	88,408		$	65,750
Work in process	65,417			47,408
Finished goods	66,907			50,738
Inventory gross	220,732			163,896
Inventory reserves	(16,346		)	(15,941		)
Inventory, net	$	204,386		$	147,955

Schedule of the annual activities included in the allowance for commitments

The following table presents the annual activities included in the inventory reserves (amounts in thousands):

Balance at March 31, 2015	$	17,499
Costs charged to expense	5,696
Write-offs	(7,326		)
Other	232
Balance at March 31, 2016	16,101
Costs charged to expense	6,163
Write-offs	(6,125		)
Other	(198		)
Balance at March 31, 2017	15,941
Costs charged to expense	4,994
Write-offs	(6,954		)
Other (1)	2,365
Balance at March 31, 2018	$	16,346

Schedule of Property, plant and equipment

	Useful life (years)	March 31,
(amounts in thousands, except years)		2018			2017
Property, plant and equipment:
Land and land improvements	20	$	66,150		$	21,642
Buildings	20 - 40	186,207			140,895
Machinery and equipment	10	895,914			783,288
Furniture and fixtures	4 - 10	72,811			68,706
Construction in progress		46,391			14,653
Other		4,457			1,403
Total property and equipment		1,271,930			1,030,587
Accumulated depreciation		(866,614		)	(821,276		)
Property, plant and equipment, net		$	405,316		$	209,311

Schedule of accrued expenses

	March 31,
(amounts in thousands)	2018		2017
Accrued expenses:
Salaries, wages, and related employee costs	$	62,778	$	29,589
Interest	396		15,603
Restructuring	8,719		984
Vacation	10,364		7,524
Anti-trust fines and settlements	33,696		—
Other	6,424		4,052
Total accrued expenses	$	122,377	$	57,752

Schedule of other non-current obligations

	March 31,
(amounts in thousands)	2018		2017
Other non-current obligations:
Pension plans	$	83,495	$	34,674
Employee separation liability	8,539		8,685
Deferred compensation	5,857		1,774
Anti-trust fines and settlements	35,263		—
Uncertain tax positions	5,704		2,891
Deferred rent	3,840		—
Return of government subsidies	4,739		—
Restructuring	1,240		15
TOKIN option valuation	—		9,900
Long-term obligation on land purchase	—		898
Long-term service contracts	—		339
Other	3,059		955
Total other non-current obligations	$	151,736	$	60,131

Schedule of other (income) expense, net

	Fiscal Years Ended March 31,
(amounts in thousands)	2018		2017			2016
Other (income) expense, net:
Net foreign exchange (gains) losses	$	13,145	$	(3,758	)	$	(3,036	)
Legal expenses/fines related to anti-trust class actions	9,900		—			—
Post retirement and pension plan non-service costs	210		1,256			1,507
Insurance proceeds	—		(423		)	—
Gain on early extinguishment of debt	486		—			—
Other	851		(946		)	688
Total other (income) expense, net	$	24,592	$	(3,871	)	$	(841	)