CONDENSED CONSOLIDATED STATEMENT OF EQUITY - 9 months ended Dec. 31, 2018 - 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)	$ 112	17,243			$ (36,906)
Non-cash stock-based compensation (in shares)		334,225
Non-cash stock-based compensation	113,713	$ 33	113,680
Restricted stock units vested (in shares)		3,300,959
Restricted stock units vested	0	$ 330	(330)
Warrant exercises	0		(51)			$ 51
Warrant exercises (in shares)						3,488
Acquisition of treasury stock (in shares)						(2,253,265)
Acquisition of treasury stock	$ (64,107)					$ (64,107)
Acquisition of treasury stock from tender offer (in shares)	(11,235,955)
Acquisition of treasury stock from tender offer	$ (503,393)					$ (503,393)
Other comprehensive income (loss):
Foreign currency translation	(2,876)				(2,876)
Net earnings	1,074,008			1,074,008
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)