Property, Plant and Equipment Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Mar. 31, 2026
Property, Plant, and Equipment [Abstract]
Land and land improvements	$ 112,500	$ 112,300
Buildings and leasehold improvements	955,700	903,600
Machinery and equipment	1,478,100	1,434,300
Capitalized Computer Hardware/Software, Gross	321,100	316,300
Radioisotope	848,900	829,900
Construction in progress	455,100	509,500
Total property, plant, and equipment	4,171,300	4,105,900
Less: accumulated depreciation and depletion	(1,999,600)	(1,944,600)
Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization	$ 2,171,700	$ 2,161,200