Quarterly report pursuant to Section 13 or 15(d)

Note 7 - Supplemental Equity and Accumulated Other Comprehensive Income (Loss) - Consolidated Changes in Equity (Details)

Note 7 - Supplemental Equity and Accumulated Other Comprehensive Income (Loss) - Consolidated Changes in Equity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Balance (in shares)	38,453,046
Balance	$ 1,381,192	$ 1,165,589
Net earnings	33,395	14,398	$ 33,395	$ 14,398
Other comprehensive income	$ 14,057	$ (8,106)
Common stock issued for exercise of options (in shares)	116,816	93,596
Common stock issued for exercise of options	$ 13,728	$ 7,855
Common stock issued for restricted stock awards	(4,890)	(1,926)
Cash dividends	(12,336)	(12,169)
Stock-based compensation expense	12,667	8,267
Common stock issued to employee stock purchase plan	1,463	1,096
Employee stock purchase plan expense	$ 286	99
Balance (in shares)	38,601,131		38,601,131
Balance	$ 1,439,285	1,174,224	$ 1,439,285	$ 1,174,224
Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance	$ (276)	$ (879)
Common Stock [Member]
Balance (in shares)	38,453,000	37,934,000
Balance	$ 385	$ 379
Common stock issued for exercise of options (in shares)	117,000	94,000
Common stock issued for exercise of options	$ 1	$ 1
Common stock issued for restricted stock awards (in shares)	25,000	50,000
Common stock issued for restricted stock awards	$ 0	$ 0
Common stock issued to employee stock purchase plan (in shares)	6,000	6,000
Common stock issued to employee stock purchase plan	$ 0	$ 0
Balance (in shares)	38,601,000	37,803,000	38,601,000	37,803,000
Balance	$ 386	$ 381	$ 386	$ 381
Additional Paid-in Capital [Member]
Balance	420,536	316,797
Common stock issued for exercise of options	13,727	7,854
Stock-based compensation expense	12,667	8,267
Common stock issued to employee stock purchase plan	1,463	1,096
Employee stock purchase plan expense	286	99
Balance	448,679	334,112	448,679	334,112
Retained Earnings [Member]
Balance	1,057,470	931,934
Net earnings	33,395	14,398
Common stock issued for restricted stock awards	(4,890)	(1,926)
Cash dividends	(12,336)	(12,169)
Balance	1,073,362	931,358	1,073,362	931,358
Retained Earnings [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance	(276)	(879)
AOCI Attributable to Parent [Member]
Balance	(97,199)	(83,521)
Balance	$ (83,142)	$ (91,627)	$ (83,142)	$ (91,627)