Shareholders' Equity - Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss)
Beginning of the period	$ 2,372,491	$ 1,567,481	$ 2,261,789	$ 1,489,268
Other comprehensive income (loss)	(3,601)	2,119	(2,104)	1,808
End of the period	2,262,683	1,705,963	2,262,683	1,705,963
Total
Accumulated Other Comprehensive Income (Loss)
Beginning of the period	(107,418)	(120,971)	(108,915)	(120,660)
End of the period	(111,019)	$ (118,852)	(111,019)	$ (118,852)
Cumulative Translation Adjustment
Accumulated Other Comprehensive Income (Loss)
Beginning of the period			(89,461)
Other comprehensive income (loss)			(2,876)
End of the period	(92,337)		(92,337)
Defined Benefit Plan
Accumulated Other Comprehensive Income (Loss)
Beginning of the period			(23,200)
Other comprehensive income (loss)			18
End of the period	(23,182)		(23,182)
Deferred Hedging Losses
Accumulated Other Comprehensive Income (Loss)
Beginning of the period			3,746
Other comprehensive income (loss)			754
End of the period	$ 4,500		$ 4,500