CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ 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		33,251,000
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	(113,971)				(113,971)
Foreign currency translation adjustments	(1,702)			(1,702)
Net unrealized gains (losses) on cash flow hedges, net of tax	(13)			(13)
Proceeds from issuances under stock-based compensation plans (in shares)		412,000
Proceeds from issuances under stock-based compensation plans	11,932	$ 3	11,929
Repurchase of restricted common stock (in shares)		(70,000)
Issuance of common stock for acquisition (in shares)		6,352,000
Issuance of common stock for acquisition	494,265	$ 64	494,201
Cash dividends	(16,952)				(16,952)
Stock-based compensation	$ 30,708		30,708
Repurchase of common stock (in shares)	(127,970)	(128,000)
Repurchase of common stock	$ (4,780)					(4,780)
Employees' tax withheld and paid for restricted stock and restricted stock units (in shares)		202,000
Employees' tax withheld and paid for restricted stock and restricted stock units	(13,864)					(13,864)
Deferred tax adjustment	39		39
Proceeds from ESPP (in shares)		62,000
Proceeds from ESPP	2,992	$ 1	2,991
Ending balance (in shares) at Dec. 31, 2018		39,677,000
Stockholders' equity, ending balance at Dec. 31, 2018	744,218	$ 884	1,416,513	1,031	170,861	(845,071)
Beginning balance (in shares) at Sep. 30, 2018		39,807,000
Stockholders' equity, beginning balance at Sep. 30, 2018	790,060	$ 884	1,404,713	5,668	218,564	(839,769)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(41,734)				(41,734)
Foreign currency translation adjustments	113			113
Net unrealized gains (losses) on cash flow hedges, net of tax	(4,750)			(4,750)
Proceeds from issuances under stock-based compensation plans (in shares)		17,000
Proceeds from issuances under stock-based compensation plans	52	$ 0	52
Repurchase of restricted common stock (in shares)		(8,000)
Cash dividends	(5,969)				(5,969)
Stock-based compensation	11,718		11,718
Repurchase of common stock (in shares)		(128,000)
Repurchase of common stock	(4,780)					(4,780)
Employees' tax withheld and paid for restricted stock and restricted stock units (in shares)		11,000
Employees' tax withheld and paid for restricted stock and restricted stock units	(522)					(522)
Deferred tax adjustment	30		30
Ending balance (in shares) at Dec. 31, 2018		39,677,000
Stockholders' equity, ending balance at Dec. 31, 2018	744,218	$ 884	1,416,513	1,031	170,861	(845,071)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact of new accounting standards adoption	(7,376)
Beginning balance (in shares) at Mar. 31, 2019		39,518,000
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	(149,264)				(149,264)
Foreign currency translation adjustments	(219)			(219)
Net unrealized gains (losses) on cash flow hedges, net of tax	(4,731)			(4,731)
Proceeds from issuances under stock-based compensation plans (in shares)		400,000
Proceeds from issuances under stock-based compensation plans	756	$ 5	751
Repurchase of restricted common stock (in shares)		(32,000)
Cash dividends	(17,910)				(17,910)
Stock-based compensation	$ 41,499		41,499
Repurchase of common stock (in shares)	0
Employees' tax withheld and paid for restricted stock and restricted stock units (in shares)		225,000
Employees' tax withheld and paid for restricted stock and restricted stock units	$ (9,670)					(9,670)
Proceeds from ESPP (in shares)		268,000
Proceeds from ESPP	6,025	$ 2	6,023
Other equity changes	(7)				(7)
Ending balance (in shares) at Dec. 31, 2019		39,929,000
Stockholders' equity, ending balance at Dec. 31, 2019	588,077	$ 891	1,479,880	(5,425)	(23,926)	(863,343)
Beginning balance (in shares) at Sep. 30, 2019		39,917,000
Stockholders' equity, beginning balance at Sep. 30, 2019	659,107	$ 890	1,465,978	(5,351)	60,545	(862,955)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(78,483)				(78,483)
Net unrealized gains (losses) on cash flow hedges, net of tax	(74)			(74)
Proceeds from issuances under stock-based compensation plans (in shares)		28,000
Proceeds from issuances under stock-based compensation plans	1	$ 1	0
Repurchase of restricted common stock (in shares)		(3,000)
Cash dividends	(5,988)				(5,988)
Stock-based compensation	13,902		13,902
Employees' tax withheld and paid for restricted stock and restricted stock units (in shares)		13,000
Employees' tax withheld and paid for restricted stock and restricted stock units	(388)					(388)
Ending balance (in shares) at Dec. 31, 2019		39,929,000
Stockholders' equity, ending balance at Dec. 31, 2019	$ 588,077	$ 891	$ 1,479,880	$ (5,425)	$ (23,926)	$ (863,343)