SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Provision for doubtful accounts and sales allowances
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 564	$ 1,221	$ 287
Charged to Expenses or Other Accounts	621	719	1,351
Deductions	(582)	(1,376)	(417)
Balance at End of Year	603	564	1,221
Provision for returns
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	7,314	6,194	6,201
Charged to Expenses or Other Accounts	35,485	27,635	25,174
Deductions	(32,258)	(26,515)	(25,181)
Balance at End of Year	10,541	7,314	6,194
Provision for promotions and rebates
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	27,737	15,401	14,803
Charged to Expenses or Other Accounts	150,085	111,244	79,983
Deductions	(146,075)	(98,908)	(79,385)
Balance at End of Year	31,747	27,737	15,401
Valuation allowance for deferred tax assets
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	1,962	1,940	3,351
Charged to Expenses or Other Accounts	1,130	1,962	0
Deductions	(883)	(1,940)	(1,411)
Balance at End of Year	$ 2,209	$ 1,962	$ 1,940