Accounts Receivable - Net, Warranty Returns (Details) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2018
Warranty Returns [Abstract]
Warranty accrual included in customer returns RGA issued	$ 6,390,000		$ 6,390,000		$ 7,204,000
Warranty accrual included in customer finished goods returns accrual	10,020,000		10,020,000		$ 9,442,000
Change in warranty return accrual [Roll Forward]
Balance at beginning of period	14,543,000	$ 12,849,000	16,646,000	$ 14,286,000
Charged to expense/additions	30,860,000	29,359,000	54,753,000	51,565,000
Amounts processed	(28,993,000)	(27,409,000)	(54,989,000)	(51,052,000)
Balance at end of period	$ 16,410,000	$ 14,799,000	$ 16,410,000	$ 14,799,000