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 at Mar. 31, 2017	$ 2,436,250	$ 116	$ 2,693,846	$ (3,472)	$ (570,921)	$ 316,681
Beginning Balance (in shares) at Mar. 31, 2017		115,917,431			23,876,143
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	79,812					79,812
Unrealized net investment gains (losses)	(6)			(6)
Unrealized net gains (losses) on derivative financial instruments	131			131
Cumulative translation adjustments	4,889			4,889
Recognition of actuarial net gains (losses) from pension and other post-retirement plan	1,353			1,353
Issuance of common stock pursuant to vesting of restricted stock units	1	$ 1
Issuance of common stock pursuant to vesting of restricted stock units (in shares)		1,216,535
Stock-based compensation expense for restricted stock units granted to employees	43,425		43,425
Issuance of common stock under employee stock purchase plan	17,849		17,849
Issuance of common stock under employee stock purchase plan (in shares)		610,947
Repurchase of treasury stock	(514,922)		(90,000)		$ (424,922)
Repurchase of treasury stock (in shares)					13,598,747
Ending Balance at Mar. 31, 2018	2,068,782	$ 117	2,665,120	2,895	$ (995,843)	396,493
Ending Balance (in shares) at Mar. 31, 2018		117,744,913			37,474,890
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(73,324)					(73,324)
Unrealized net investment gains (losses)	60			60
Unrealized net gains (losses) on derivative financial instruments	(87)			(87)
Cumulative translation adjustments	(3,229)			(3,229)
Recognition of actuarial net gains (losses) from pension and other post-retirement plan	(2,278)			(2,278)
Issuance of common stock pursuant to vesting of restricted stock units	3	$ 3
Issuance of common stock pursuant to vesting of restricted stock units (in shares)		1,438,219
Stock-based compensation expense for restricted stock units granted to employees	51,945		51,945
Issuance of common stock under employee stock purchase plan	15,074		15,074
Issuance of common stock under employee stock purchase plan (in shares)		577,000
Repurchase of treasury stock	(26,437)		96,783		$ (123,220)
Repurchase of treasury stock (in shares)					4,674,881
Ending Balance at Mar. 31, 2019	2,065,433	$ 120	2,828,922	(2,639)	$ (1,119,063)	358,093
Ending Balance (in shares) at Mar. 31, 2019		119,760,132			42,149,771
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(2,754)					(2,754)
Unrealized net investment gains (losses)	126			126
Unrealized net gains (losses) on derivative financial instruments	(57)			(57)
Cumulative translation adjustments	(1,644)			(1,644)
Recognition of actuarial net gains (losses) from pension and other post-retirement plan	1,054			1,054
Issuance of common stock pursuant to vesting of restricted stock units	2	$ 2
Issuance of common stock pursuant to vesting of restricted stock units (in shares)		1,651,284
Stock-based compensation expense for restricted stock units granted to employees	48,404		48,404
Issuance of common stock under employee stock purchase plan	14,227		14,227
Issuance of common stock under employee stock purchase plan (in shares)		594,661
Repurchase of treasury stock	(186,872)				$ (186,872)
Repurchase of treasury stock (in shares)					7,635,400
Ending Balance at Mar. 31, 2020	$ 1,937,919	$ 122	$ 2,891,553	$ (3,160)	$ (1,305,935)	$ 355,339
Ending Balance (in shares) at Mar. 31, 2020		122,006,077			49,785,171