LOSS PER SHARE AND STOCKHOLDERS’ EQUITY: Narrative (Details) - USD ($) shares in Millions	6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Acquisition of treasury stock	$ 42,312,000	$ 100,473,000
Treasury stock, at cost	2,022,353,000		$ 1,974,286,000
Accumulated other comprehensive income (loss), foreign currency translation adjustment	6,900,000		$ 5,700,000
Common Stock Repurchase Program
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock repurchase program, authorized amount	$ 1,000,000,000.0
Acquisition of treasury stock (in shares)	1.3
Acquisition of treasury stock	$ 42,300,000
Treasury stock, at cost (in shares)	28.2
Treasury stock, at cost	$ 673,600,000
Stock repurchase program, remaining amount	$ 326,400,000