CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Treasury Stock [Member]
Beginning balance (in shares) at Mar. 31, 2018		33,251
Stockholders' equity, beginning balance at Mar. 31, 2018	$ 352,970	$ 816	$ 876,645	$ 2,870	$ 299,066	$ (826,427)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(72,238)				(72,238)
Foreign currency translation adjustments	(1,815)			(1,815)
Net unrealized gains (losses) on cash flow hedges, net of tax	4,737			4,737
Proceeds from issuances under stock-based compensation plans (in shares)		395
Proceeds from issuances under stock-based compensation plans	11,880	$ 3	11,877
Repurchase of restricted common stock (in shares)		(62)
Issuance of common stock for acquisition (in shares)		6,352
Issuance of common stock for acquisition	494,265	$ 64	494,201
Cash dividends	(10,982)				(10,982)
Stock-based compensation	18,990		18,990
Employees' tax withheld and paid for restricted stock and restricted stock units (in shares)		191
Employees' tax withheld and paid for restricted stock and restricted stock units	(13,342)					(13,342)
Deferred tax adjustment	9		9
Proceeds from ESPP (in shares)		62
Proceeds from ESPP	2,992	$ 1	2,991
Ending balance (in shares) at Sep. 30, 2018		39,807
Stockholders' equity, ending balance at Sep. 30, 2018	790,060	$ 884	1,404,713	5,668	218,564	(839,769)
Beginning balance (in shares) at Jun. 30, 2018		33,372
Stockholders' equity, beginning balance at Jun. 30, 2018	374,533	$ 819	895,350	6,585	311,241	(839,462)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(86,709)				(86,709)
Foreign currency translation adjustments	(1,815)			(1,815)
Net unrealized gains (losses) on cash flow hedges, net of tax	898			898
Proceeds from issuances under stock-based compensation plans (in shares)		34
Proceeds from issuances under stock-based compensation plans	1,322	$ 0	1,322
Repurchase of restricted common stock (in shares)		(9)
Issuance of common stock for acquisition (in shares)		6,352
Issuance of common stock for acquisition	494,265	$ 64	494,201
Cash dividends	(5,968)				(5,968)
Stock-based compensation	10,840		10,840
Employees' tax withheld and paid for restricted stock and restricted stock units (in shares)		4
Employees' tax withheld and paid for restricted stock and restricted stock units	(307)					(307)
Deferred tax adjustment	9		9
Proceeds from ESPP (in shares)		62
Proceeds from ESPP	2,992	$ 1	2,991
Ending balance (in shares) at Sep. 30, 2018		39,807
Stockholders' equity, ending balance at Sep. 30, 2018	790,060	$ 884	1,404,713	5,668	218,564	(839,769)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact of new accounting standards adoption	(7,376)
Beginning balance (in shares) at Mar. 31, 2019		39,518
Stockholders' equity, beginning balance at Mar. 31, 2019	721,687	$ 884	1,431,607	(475)	143,344	(853,673)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(70,781)				(70,781)
Foreign currency translation adjustments	(219)			(219)
Net unrealized gains (losses) on cash flow hedges, net of tax	(4,657)			(4,657)
Proceeds from issuances under stock-based compensation plans (in shares)		372
Proceeds from issuances under stock-based compensation plans	755	$ 4	751
Repurchase of restricted common stock (in shares)		(29)
Cash dividends	(11,922)				(11,922)
Stock-based compensation	27,597		27,597
Employees' tax withheld and paid for restricted stock and restricted stock units (in shares)		212
Employees' tax withheld and paid for restricted stock and restricted stock units	(9,282)					(9,282)
Proceeds from ESPP (in shares)		268
Proceeds from ESPP	6,025	$ 2	6,023
Other equity changes	(7)				(7)
Ending balance (in shares) at Sep. 30, 2019		39,917
Stockholders' equity, ending balance at Sep. 30, 2019	659,107	$ 890	1,465,978	(5,351)	60,545	(862,955)
Beginning balance (in shares) at Jun. 30, 2019		39,578
Stockholders' equity, beginning balance at Jun. 30, 2019	669,498	$ 887	1,445,097	(6,628)	92,437	(862,295)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(25,910)				(25,910)
Net unrealized gains (losses) on cash flow hedges, net of tax	1,277			1,277
Proceeds from issuances under stock-based compensation plans (in shares)		101
Proceeds from issuances under stock-based compensation plans	166	$ 1	165
Repurchase of restricted common stock (in shares)		(9)
Cash dividends	(5,982)				(5,982)
Stock-based compensation	14,693		14,693
Employees' tax withheld and paid for restricted stock and restricted stock units (in shares)		(21)
Employees' tax withheld and paid for restricted stock and restricted stock units	(660)					(660)
Proceeds from ESPP (in shares)		268
Proceeds from ESPP	6,025	$ 2	6,023
Ending balance (in shares) at Sep. 30, 2019		39,917
Stockholders' equity, ending balance at Sep. 30, 2019	$ 659,107	$ 890	$ 1,465,978	$ (5,351)	$ 60,545	$ (862,955)