CONDENSED CONSOLIDATED STATEMENT OF EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional paid-in Capital	Retained earnings	Accumulated other comprehensive income (loss)	Treasury Stock
Balance, beginning of the period (in shares) at Mar. 31, 2018		136,079,676				(58,304,917)
Balance, beginning of the period at Mar. 31, 2018	$ 749,095	$ 13,609	$ 1,235,679	$ 628,331	$ 10,767	$ (1,139,291)
Increase (Decrease) in Stockholders' Equity
Employee stock awards, benefit plans and other issuances (in shares)		1,122,879				(953,523)
Employee stock awards, benefit plans and other issuances	(19,551)	$ 113	17,242			$ (36,906)
Non-cash stock-based compensation (in shares)		334,225
Non-cash stock-based compensation	50,852	$ 33	50,819
Non-cash stock-based compensation from discontinued operations	62,861		62,861
Restricted stock units vested (in shares)		3,300,959
Restricted stock units vested	0	$ 329	(329)
Acquisition of treasury stock (in shares)						(2,253,265)
Acquisition of treasury stock	(64,107)					$ (64,107)
Other comprehensive income (loss):
Foreign currency translation	(2,876)				(2,876)
Net earnings (loss)	1,074,008			1,074,008
Cumulative-effect adjustment from adoption of ASU 2014-09	12,727			12,727
Warrant exercises	0		(51)			$ 51
Warrant exercises (in shares)						3,488
Acquisition of treasury stock from tender offer (in shares)						11,235,955
Tender offer	(503,393)					$ (503,393)
Balance, end of the period (in shares) at Dec. 31, 2018		140,837,739				(72,744,172)
Balance, end of the period at Dec. 31, 2018	1,359,616	$ 14,084	1,366,221	1,715,066	7,891	$ (1,743,646)
Balance, beginning of the period (in shares) at Sep. 30, 2018		138,356,148				(60,650,555)
Balance, beginning of the period at Sep. 30, 2018	760,678	$ 13,836	1,277,614	658,666	10,192	$ (1,199,630)
Increase (Decrease) in Stockholders' Equity
Employee stock awards, benefit plans and other issuances (in shares)		683,542				(457,468)
Employee stock awards, benefit plans and other issuances	(13,048)	$ 69	9,165			$ (22,282)
Non-cash stock-based compensation (in shares)		93,641
Non-cash stock-based compensation	16,760	$ 9	16,751
Non-cash stock-based compensation from discontinued operations	62,861		62,861
Restricted stock units vested (in shares)		1,704,408
Restricted stock units vested	0	$ 170	(170)
Acquisition of treasury stock (in shares)						(400,194)
Acquisition of treasury stock	(18,341)					$ (18,341)
Other comprehensive income (loss):
Foreign currency translation	(2,301)				(2,301)
Net earnings (loss)	1,056,400			1,056,400
Acquisition of treasury stock from tender offer (in shares)						11,235,955
Tender offer	(503,393)					$ (503,393)
Balance, end of the period (in shares) at Dec. 31, 2018		140,837,739				(72,744,172)
Balance, end of the period at Dec. 31, 2018	1,359,616	$ 14,084	1,366,221	1,715,066	7,891	$ (1,743,646)
Balance, beginning of the period (in shares) at Mar. 31, 2019		141,865,888				(73,167,892)
Balance, beginning of the period at Mar. 31, 2019	1,330,832	$ 14,187	1,406,813	1,669,605	7,801	$ (1,767,574)
Increase (Decrease) in Stockholders' Equity
Employee stock awards, benefit plans and other issuances (in shares)		194,743				(350,847)
Employee stock awards, benefit plans and other issuances	(14,652)	$ 19	3,386			$ (18,057)
Non-cash stock-based compensation (in shares)		64,130
Non-cash stock-based compensation	48,952	$ 7	48,945
Restricted stock units vested (in shares)		884,235
Restricted stock units vested	0	$ 88	(88)
Acquisition of treasury stock (in shares)						(2,558,883)
Acquisition of treasury stock	(121,188)					$ (121,188)
Other comprehensive income (loss):
Foreign currency translation	(1,025)				(1,025)
Net earnings (loss)	(120,382)			(120,382)
Liability-classified restricted stock units vested (in shares)		418,850
Liability-classified restricted stock units vested	17,704	$ 42	17,662
Acquisition-related replacement stock options	2,300		2,300
Balance, end of the period (in shares) at Dec. 31, 2019		143,427,846				(76,077,622)
Balance, end of the period at Dec. 31, 2019	1,142,541	$ 14,343	1,479,018	1,549,223	6,776	$ (1,906,819)
Balance, beginning of the period (in shares) at Sep. 30, 2019		143,096,272				(75,558,291)
Balance, beginning of the period at Sep. 30, 2019	1,186,358	$ 14,310	1,460,120	1,587,263	6,619	$ (1,881,954)
Increase (Decrease) in Stockholders' Equity
Employee stock awards, benefit plans and other issuances (in shares)		75,557				(95,378)
Employee stock awards, benefit plans and other issuances	(2,839)	$ 7	1,304			$ (4,150)
Non-cash stock-based compensation (in shares)		5,935
Non-cash stock-based compensation	17,620	$ 1	17,619
Restricted stock units vested (in shares)		250,082
Restricted stock units vested	0	$ 25	(25)
Acquisition of treasury stock (in shares)						(423,953)
Acquisition of treasury stock	(20,715)					$ (20,715)
Other comprehensive income (loss):
Foreign currency translation	157				157
Net earnings (loss)	(38,040)			(38,040)
Balance, end of the period (in shares) at Dec. 31, 2019		143,427,846				(76,077,622)
Balance, end of the period at Dec. 31, 2019	$ 1,142,541	$ 14,343	$ 1,479,018	$ 1,549,223	$ 6,776	$ (1,906,819)