Quarterly Summary of Information (Details) - USD ($) $ / shares in Units, $ 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
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 394,130	$ 873,800	$ 501,913	$ 250,594	$ 400,684	$ 810,478	$ 482,460	$ 209,717	$ 2,020,437	$ 1,903,339	$ 1,790,147
Gross profit	203,305	470,093	251,887	114,965	192,429	423,471	225,117	90,625	1,040,250	931,642	835,235
(Loss) income from operations	31,604	244,718	90,412	(39,414)	18,294	193,191	67,355	(56,256)	327,320	222,584	(1,919)
Net income	$ 23,969	$ 196,374	$ 74,372	$ (30,407)	$ 20,615	$ 86,341	$ 49,559	$ (42,121)	$ 264,308	$ 114,394	$ 5,710
Net (loss) income per share
Basic (in dollars per share)	$ 0.82	$ 6.74	$ 2.49	$ (1.00)	$ 0.66	$ 2.71	$ 1.55	$ (1.32)	$ 8.92	$ 3.60	$ 0.18
Diluted (in dollars per share)	$ 0.82	$ 6.68	$ 2.48	$ (1.00)	$ 0.66	$ 2.69	$ 1.54	$ (1.32)	$ 8.84	$ 3.58	$ 0.18
Restructuring charges									$ 295	$ 1,667	$ 28,984
Accounting Standards Update 2014-09 | Direct-to-Consumer
Condensed Financial Statements, Captions [Line Items]
Net sales						$ (12,000)