SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Provision for doubtful accounts and sales allowances
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 873	$ 603	$ 564
SEC Schedule, 12-09, Valuation Allowances and Reserves, Business Acquired	3,928	0	0
Charged to Expenses or Other Accounts	4,332	784	621
Deductions	(4,176)	(514)	(582)
Balance at End of Year	4,956	873	603
Provision for returns
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	10,225	10,541	7,314
SEC Schedule, 12-09, Valuation Allowances and Reserves, Business Acquired	(10,225)	0	0
Charged to Expenses or Other Accounts	0	30,472	35,485
Deductions	0	(30,788)	(32,258)
Balance at End of Year	0	10,225	10,541
Provision for promotions and rebates
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	38,284	31,747	27,737
SEC Schedule, 12-09, Valuation Allowances and Reserves, Business Acquired	44,136	0	0
Charged to Expenses or Other Accounts	417,422	183,929	150,085
Deductions	(376,789)	(177,392)	(146,075)
Balance at End of Year	123,053	38,284	31,747
Valuation allowance for deferred tax assets
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	2,514	2,209	1,962
SEC Schedule, 12-09, Valuation Allowances and Reserves, Business Acquired	8,068
Charged to Expenses or Other Accounts	7,469	981	1,130
Deductions	(2,264)	(676)	(883)
Balance at End of Year	$ 15,787	$ 2,514	$ 2,209