Business Segments - Information on Operating and Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information, Profit (Loss):
Total revenues	$ 269,181	$ 229,394
Cost of sales	110,169	95,526
Gross profit	159,012	133,868
Advertising and marketing	39,439	27,750
Contribution margin	119,573	106,118
Other operating expenses	28,231	25,999
Operating income	91,342	80,119
North American OTC Healthcare
Segment Reporting Information, Profit (Loss):
Total revenues	242,393	210,658
International OTC Healthcare
Segment Reporting Information, Profit (Loss):
Total revenues	26,788	18,736
Operating Segments | North American OTC Healthcare
Segment Reporting Information, Profit (Loss):
Total revenues	242,393	210,658
Cost of sales	99,404	87,827
Gross profit	142,989	122,831
Advertising and marketing	35,230	24,680
Contribution margin	107,759	98,151
Operating Segments | International OTC Healthcare
Segment Reporting Information, Profit (Loss):
Total revenues	26,788	18,736
Cost of sales	10,765	7,699
Gross profit	16,023	11,037
Advertising and marketing	4,209	3,070
Contribution margin	11,814	7,967
Intersegment Eliminations | North American OTC Healthcare
Segment Reporting Information, Profit (Loss):
Total revenues	$ 1,000	$ 1,000