Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock Voting	Additional Paid In Capital	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Retained Earnings
Beginning balance (in shares) at Mar. 31, 2020		122,006,077			(49,785,171)
Beginning balance at Mar. 31, 2020	$ 1,937,919	$ 122	$ 2,891,553	$ (3,160)	$ (1,305,935)	$ 355,339
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(21,106)					(21,106)
Unrealized net investment losses	(107)			(107)
Unrealized net gains (loss) on derivative financial instruments	116			116
Cumulative translation adjustments	1,893			1,893
Issuance of common stock pursuant to vesting of restricted stock units (in shares)		1,555,056
Issuance of common stock pursuant to vesting of restricted stock units	1	$ 1
Stock-based compensation expense for restricted stock units granted to employees	26,729		26,729
Issuance of common stock under employee stock purchase plan (in shares)		279,812
Issuance of common stock under employee stock purchase plan	6,475		6,475
Repurchase of treasury stock (in shares)					(481,739)
Repurchase of treasury stock	(12,600)				$ (12,600)
Ending balance (in shares) at Sep. 30, 2020		123,840,945			(50,266,910)
Ending balance at Sep. 30, 2020	1,939,320	$ 123	2,924,757	(1,258)	$ (1,318,535)	334,233
Beginning balance (in shares) at Jun. 30, 2020		122,353,504			(49,898,334)
Beginning balance at Jun. 30, 2020	1,929,817	$ 122	2,903,055	(2,241)	$ (1,309,038)	337,919
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(3,686)					(3,686)
Unrealized net investment losses	(33)			(33)
Unrealized net gains (loss) on derivative financial instruments	76			76
Cumulative translation adjustments	940			940
Issuance of common stock pursuant to vesting of restricted stock units (in shares)		1,207,629
Issuance of common stock pursuant to vesting of restricted stock units	1	$ 1
Stock-based compensation expense for restricted stock units granted to employees	15,227		15,227
Issuance of common stock under employee stock purchase plan (in shares)		279,812
Issuance of common stock under employee stock purchase plan	6,475		6,475
Repurchase of treasury stock (in shares)					(368,576)
Repurchase of treasury stock	(9,497)				$ (9,497)
Ending balance (in shares) at Sep. 30, 2020		123,840,945			(50,266,910)
Ending balance at Sep. 30, 2020	1,939,320	$ 123	2,924,757	(1,258)	$ (1,318,535)	334,233
Beginning balance (in shares) at Mar. 31, 2021		124,197,974			(50,446,359)
Beginning balance at Mar. 31, 2021	2,005,779	$ 124	2,955,400	(1,940)	$ (1,322,496)	374,691
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(3,445)					(3,445)
Unrealized net investment losses	(5)			(5)
Unrealized net gains (loss) on derivative financial instruments	47			47
Cumulative translation adjustments	(33)			(33)
Issuance of common stock pursuant to vesting of restricted stock units (in shares)		1,659,576
Issuance of common stock pursuant to vesting of restricted stock units	2	$ 2
Stock-based compensation expense for restricted stock units granted to employees	29,414		29,414
Issuance of common stock under employee stock purchase plan (in shares)		251,308
Issuance of common stock under employee stock purchase plan	6,890		6,890
Repurchase of treasury stock (in shares)					(1,444,838)
Repurchase of treasury stock	(39,645)				$ (39,645)
Ending balance (in shares) at Sep. 30, 2021		126,108,858			(51,891,197)
Ending balance at Sep. 30, 2021	1,999,004	$ 126	2,991,704	(1,931)	$ (1,362,141)	371,246
Beginning balance (in shares) at Jun. 30, 2021		124,694,737			(50,610,492)
Beginning balance at Jun. 30, 2021	2,002,955	$ 124	2,968,631	(1,877)	$ (1,327,273)	363,350
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	7,896					7,896
Unrealized net investment losses	0
Unrealized net gains (loss) on derivative financial instruments	(2)			(2)
Cumulative translation adjustments	(52)			(52)
Issuance of common stock pursuant to vesting of restricted stock units (in shares)		1,162,813
Issuance of common stock pursuant to vesting of restricted stock units	2	$ 2
Stock-based compensation expense for restricted stock units granted to employees	16,183		16,183
Issuance of common stock under employee stock purchase plan (in shares)		251,308
Issuance of common stock under employee stock purchase plan	6,890		6,890
Repurchase of treasury stock (in shares)					(1,280,705)
Repurchase of treasury stock	(34,868)				$ (34,868)
Ending balance (in shares) at Sep. 30, 2021		126,108,858			(51,891,197)
Ending balance at Sep. 30, 2021	$ 1,999,004	$ 126	$ 2,991,704	$ (1,931)	$ (1,362,141)	$ 371,246