Summary Financial Information (Statements of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Gross profit	$ 76,045	$ 73,405	$ 75,900	$ 79,647	$ 74,716	$ 69,137	$ 71,778	$ 69,430	$ 304,997	$ 285,061	$ 192,885
Selling expenses									97,925	101,956	77,319
General and administrative expenses									83,567	85,605	72,129
Amortization of intangibles									14,900	15,552	8,105
Income from operations	$ 24,468	$ 6,646	$ 24,825	$ 13,503	$ 15,807	$ 13,710	$ 19,219	$ 19,595	69,442	68,331	23,725
Interest and debt expense									17,144	19,733	10,966
Investment (income) loss, net									(727)	(157)	(462)
Foreign currency exchange loss (gain), net									843	1,539	1,232
Other (income) expense, net									(716)	(2,469)	(2,341)
Income from continuing operations before income tax expense									52,898	49,685	13,027
Income tax expense									10,321	27,620	4,043
Net income									$ 42,577	$ 22,065	$ 8,984