Business Segments (Information on Operating and Reportable Segments) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information, Profit (Loss):
Total revenues	$ 237,422	$ 238,069	$ 466,816	$ 470,223
Cost of sales	99,761	101,318	195,287	199,405
Gross profit	137,661	136,751	271,529	270,818
Advertising and marketing	38,341	38,667	66,091	73,468
Contribution margin	99,320	98,084	205,438	197,350
Other operating expenses	26,417	28,736	52,416	56,516
Operating income	72,903	69,348	153,022	140,834
North American OTC Healthcare
Segment Reporting Information, Profit (Loss):
Total revenues	216,575	213,878	427,233	424,662
International OTC Healthcare
Segment Reporting Information, Profit (Loss):
Total revenues	20,847	24,191	39,583	45,561
Operating Segments | North American OTC Healthcare
Segment Reporting Information, Profit (Loss):
Total revenues	216,575	213,878	427,233	424,662
Cost of sales	91,069	92,931	178,896	181,742
Gross profit	125,506	120,947	248,337	242,920
Advertising and marketing	34,014	34,595	58,694	65,609
Contribution margin	91,492	86,352	189,643	177,311
Operating Segments | International OTC Healthcare
Segment Reporting Information, Profit (Loss):
Total revenues	20,847	24,191	39,583	45,561
Cost of sales	8,692	8,387	16,391	17,663
Gross profit	12,155	15,804	23,192	27,898
Advertising and marketing	4,327	4,072	7,397	7,859
Contribution margin	7,828	11,732	15,795	20,039
Intersegment Eliminations | North American OTC Healthcare
Segment Reporting Information, Profit (Loss):
Total revenues	$ 600	$ 800	$ 1,600	$ 1,600