STOCKHOLDERS' EQUITY: - Narrative (Details) - USD ($)		9 Months Ended	12 Months Ended			17 Months Ended
	Oct. 25, 2018	Dec. 31, 2018	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2020
Stockholders' Equity, Number of Shares, Par Value and Other Disclosures [Abstract]
Common stock, shares authorized			200,000,000	200,000,000		200,000,000
Common stock, par or stated value (in dollars per share)			$ 0.10	$ 0.10		$ 0.10
Preferred stock, shares authorized			1,000,000	1,000,000		1,000,000
Preferred stock, par or stated value (in dollars per shares)			$ 1.00	$ 1.00		$ 1.00
Stockholders' Equity Note [Abstract]
Acquisition of treasury stock (in shares)						26,900,000
Acquisition of treasury stock			$ 182,190,000	$ 74,421,000	$ 88,884,000	$ 631,200,000
Stock repurchase program, remaining amount			$ 368,800,000			$ 368,800,000
Treasury stock, at cost (in shares)			78,100,000	73,200,000		78,100,000
Acquisition of treasury stock from tender offer			$ 0	$ 503,393,000	$ 0
Total shares reserved for issuance since inception of the stock option and equity compensation plans (in shares)				42,300,000
Restricted stock units | Share-based Payment Arrangement, Tranche Three
Stockholders' Equity Note [Abstract]
Incremental compensation cost			$ 14,300,000
Forfeited in period (in shares)				500,000
Compensation costs				$ 19,800,000
Incremental compensation cost				5,500,000
Performance stock | Shares Vesting Based On Relevant Performance Period At March 31 2018
Stockholders' Equity Note [Abstract]
Award vesting rights percentage			0.00%
Time Vesting Restricted Stock Units
Stockholders' Equity Note [Abstract]
Incremental compensation cost				$ 27,000,000.0
Conversion percentage				200.00%
Amended Common Stock Repurchase Plan
Stockholders' Equity Note [Abstract]
Stock repurchase program, authorized amount	$ 500,000,000
Acquisition of treasury stock (in shares)				2,400,000	3,300,000
Acquisition of treasury stock				$ 74,400,000	$ 88,900,000
Dutch Auction Tender Offer
Stockholders' Equity Note [Abstract]
Stock repurchase program, authorized amount	$ 500,000,000
Repurchase of common stock, percentage	2.00%		14.20%
Treasury stock, at cost (in shares)		11,200,000
Treasury stock cost per share (in dollar per share)		$ 44.50
Acquisition of treasury stock from tender offer		$ 503,400,000
Common Stock Repurchase Program
Stockholders' Equity Note [Abstract]
Stock repurchase program, authorized amount	$ 1,000,000,000.0
Acquisition of treasury stock (in shares)			4,400,000
Acquisition of treasury stock			$ 182,200,000
Amended and Restated 2005 Equity Compensation Plan
Stockholders' Equity Note [Abstract]
Shares which remained available for future grants (in shares)				37,900,000	32,900,000
Total shares reserved for issuance since inception of the stock option and equity compensation plans (in shares)				34,500,000