Debt (Narratives) (Details)	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2018 CNY (¥)	Jan. 31, 2017 USD ($)
Line of Credit Facility [Line Items]
Certain Loans Acquired in Transfer Accounted for as Available-for-sale Debt Securities, Acquired, at Acquisition, at Fair Value	$ 2,608,000		$ 0	$ 2,608,000
Outstanding letters of credit			4,478,000
Payments of financing costs			(619,000)	(19,409,000)	$ 0
Carrying amount of the Company's revolving credit facility	$ 432,500,000		375,463,000	432,500,000	103,125,000
Gain (Loss) on Extinguishment of Debt			$ 0	$ (1,303,000)	$ 0
Stated interest rate percentage	3.00%		3.00%	3.00%		3.00%
New Senior Subordinated note issued			$ 445,000,000
Secured Long-term Debt, Noncurrent	$ 432,500,000			$ 432,500,000
Document Fiscal Year Focus			2018
Line of Credit Facility, Fair Value of Amount Outstanding			$ 0
Gross balance of deferred costs	14,690,000			14,690,000
Accumulated amortization balances	350,000		2,447,000	350,000
Capital Lease Obligations	551,000		98,000	551,000
Capital lease obligations	551,000			551,000
Debt obligations			5,176,000
Amount drawn on unsecured credit lines			0
Debt Instrument, Unamortized Discount, Noncurrent	(14,340,000)		(12,243,000)	(14,340,000)
Long-term Debt	(421,319,000)		(363,318,000)	(421,319,000)
Maximum
Line of Credit Facility [Line Items]
Long-term Debt			(445,000,000)
Minimum
Line of Credit Facility [Line Items]
Outstanding letters of credit			$ 745,000
Capital Lease Obligations
Line of Credit Facility [Line Items]
Term under lease agreement			10 years
Foreign Line of Credit
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 17,877,000
Outstanding borrowings			$ 11,668,000
Line of Credit
Line of Credit Facility [Line Items]
Gross balance of deferred costs	2,789,000			2,789,000
STAHL China Loan [Member]
Line of Credit Facility [Line Items]
Stated interest rate percentage			4.00%			4.00%
New Senior Subordinated note issued			$ 2,608,000			¥ 18,000,000
Replaced Revolving Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Month-end Outstanding Amount		$ 225,000,000.0
Debt Instrument, Fee		652000
Gross balance of deferred costs	763,000		605,000	763,000
Amount drawn on unsecured credit lines		$ 131,500,000.0
Other Current Liabilities [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Periodic Payment, Principal	12,500,000	$ 9,375,000
Capital lease obligations			64,000
Standby Letters of Credit
Line of Credit Facility [Line Items]
Outstanding letters of credit			3,733,000
STAHL [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			100,000,000				$ 545,000,000
Secured Debt, Current			4,450,000
Long-term Debt			(545,000,000)
STAHL [Member] | Line of Credit
Line of Credit Facility [Line Items]
Secured Long-term Debt, Noncurrent			445,000,000
STAHL [Member] | New Revolving Credit Facility
Line of Credit Facility [Line Items]
Secured Long-term Debt, Noncurrent			100,000,000
Accumulated amortization balances			651,000
STAHL [Member] | Other Current Liabilities [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Periodic Payment, Principal			$ 57,037,000
Magnetek [Member] | Replaced Revolving Credit [Member]
Line of Credit Facility [Line Items]
Accumulated amortization balances	$ 93,000			$ 93,000