Reportable Operating Segments (Details)	3 Months Ended		6 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) segment	Sep. 30, 2017 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			6
Net sales	$ 501,913,000	$ 482,460,000	$ 752,507,000	$ 692,177,000
(Loss) income from operations	90,412,000	67,355,000	50,998,000	11,099,000
Total assets	1,423,968,000		1,423,968,000		$ 1,264,379,000
Unallocated cash and cash equivalents	182,192,000	230,586,000	182,192,000	230,586,000	429,970,000	$ 291,764,000
Unallocated deferred tax assets	38,878,000		38,878,000		38,381,000
Reportable segments
Segment Reporting Information [Line Items]
Total assets	977,616,000		977,616,000		582,360,000
Reportable segments | UGG brand wholesale
Segment Reporting Information [Line Items]
Total assets	661,623,000		661,623,000		229,894,000
Reportable segments | HOKA brand wholesale
Segment Reporting Information [Line Items]
Total assets	71,919,000		71,919,000		65,943,000
Reportable segments | Teva brand wholesale
Segment Reporting Information [Line Items]
Total assets	46,021,000		46,021,000		85,980,000
Reportable segments | Sanuk brand wholesale
Segment Reporting Information [Line Items]
Total assets	52,646,000		52,646,000		79,322,000
Reportable segments | Other brands wholesale
Segment Reporting Information [Line Items]
Total assets	41,666,000		41,666,000		8,866,000
Reportable segments | Direct-to-Consumer
Segment Reporting Information [Line Items]
Total assets	103,741,000		103,741,000		112,355,000
Segment reconciling items
Segment Reporting Information [Line Items]
Intersegment profit			0
(Loss) income from operations	(62,187,000)	(57,647,000)	(118,388,000)	(111,166,000)
Unallocated cash and cash equivalents	182,192,000		182,192,000		429,970,000
Unallocated deferred tax assets	38,878,000		38,878,000		38,381,000
Unallocated other corporate assets	225,282,000		225,282,000		$ 213,668,000
Wholesale | Reportable segments | UGG brand wholesale
Segment Reporting Information [Line Items]
Net sales	319,589,000	322,050,000	400,942,000	385,323,000
(Loss) income from operations	134,029,000	117,218,000	139,898,000	116,197,000
Wholesale | Reportable segments | HOKA brand wholesale
Segment Reporting Information [Line Items]
Net sales	43,561,000	35,699,000	83,515,000	62,237,000
(Loss) income from operations	8,170,000	7,549,000	13,898,000	8,809,000
Wholesale | Reportable segments | Teva brand wholesale
Segment Reporting Information [Line Items]
Net sales	15,878,000	16,494,000	49,074,000	48,617,000
(Loss) income from operations	1,847,000	1,916,000	9,911,000	6,859,000
Wholesale | Reportable segments | Sanuk brand wholesale
Segment Reporting Information [Line Items]
Net sales	10,933,000	12,087,000	31,436,000	34,307,000
(Loss) income from operations	291,000	1,228,000	4,491,000	5,645,000
Wholesale | Reportable segments | Other brands wholesale
Segment Reporting Information [Line Items]
Net sales	18,064,000	4,822,000	20,701,000	5,249,000
(Loss) income from operations	5,287,000	494,000	5,637,000	260,000
Directly to Consumer | Reportable segments | Direct-to-Consumer
Segment Reporting Information [Line Items]
Net sales	93,888,000	91,308,000	166,839,000	156,444,000
(Loss) income from operations	$ 2,975,000	$ (3,403,000)	$ (4,449,000)	$ (15,505,000)