STOCKHOLDERS' EQUITY: - Narrative (Details) - USD ($)			12 Months Ended
	Dec. 13, 2018	Oct. 25, 2018	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019	Nov. 03, 2020
Equity [Abstract]
Common stock, shares authorized			200,000,000	200,000,000
Common stock, par or stated value (in dollars per share)			$ 0.10	$ 0.10
Preferred stock, shares authorized			1,000,000	1,000,000
Preferred stock, par or stated value (in dollars per shares)			$ 1.00	$ 1.00
Equity, Class of Treasury Stock [Line Items]
Acquisition of treasury stock			$ 42,312,000	$ 182,190,000	$ 74,421,000
Treasury stock, at cost (in shares)			79,600,000	78,100,000
Treasury stock, at cost			$ 2,026,518,000	$ 1,974,286,000
Acquisition of treasury stock from tender offer			0	0	$ 503,393,000
Accumulated other comprehensive income (loss), foreign currency translation adjustment			$ 7,500,000	$ 5,700,000
Restricted stock units | Share-based Payment Arrangement, Tranche Three
Equity, Class of Treasury Stock [Line Items]
Forfeited in period (in shares)			700,000		500,000
Compensation costs			$ 21,400,000		$ 19,800,000
Incremental compensation cost			8,400,000		14,300,000
Accelerated original grant date fair value compensation cost			$ 13,000,000.0		5,500,000
Time Vesting Restricted Stock Units
Equity, Class of Treasury Stock [Line Items]
Incremental compensation cost					$ 27,000,000.0
Conversion percentage					200.00%
Common Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount						$ 1,000,000,000.0
Acquisition of treasury stock (in shares)			1,300,000	4,400,000	2,400,000
Acquisition of treasury stock			$ 42,300,000	$ 182,200,000	$ 74,400,000
Treasury stock, at cost (in shares)			28,200,000
Treasury stock, at cost			$ 673,600,000
Stock repurchase program, remaining amount			$ 326,400,000
Dutch Auction Tender Offer
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount		$ 500,000,000
Treasury stock, at cost (in shares)	11,200,000
Repurchase of common stock, percentage		2.00%	14.20%
Treasury stock cost per share (in dollar per share)	$ 44.50
Acquisition of treasury stock from tender offer	$ 503,400,000