Acquisitions (Narratives) (Details) - USD ($)	3 Months Ended			6 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2018	Jun. 30, 2016
Business Acquisition [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 217,142,000		$ 212,828,000	$ 442,134,000	$ 416,554,000
Business Acquisition, Period Results Included in Combined Entity	24,825,000		19,219,000	38,328,000	38,814,000
Severance Costs				1,602,000
Proceeds from Secured Lines of Credit		$ 445,000,000
Goodwill	329,062,000			329,062,000		$ 347,434,000
Accrued liabilities	95,607,000			95,607,000		$ 99,963,000
Ergomatic Products LLC [Member]
Business Acquisition [Line Items]
Business Combination, Contingent Consideration, Asset							$ 588,000
Restricted Cash and Investments, Noncurrent	294,000		294,000
Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Business Acquisition [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	9,463,000		10,358,000	20,900,000	19,042,000
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	1,455,000		$ 508,000	2,116,000	$ 449,000
Goodwill	7,392,000			7,392,000
Accrued liabilities	$ 2,341,000			$ 2,341,000