Revenue Recognition (Revenue disaggregated by timing of revenue recognition) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Revenue From Contract With Customer [Abstract]
Revenues recognized over time	$ 182,278	$ 147,565	$ 2,814,732
Revenues recognized at point in time	396,600	309,804	305,408
Total revenues recognized under ASC 606	578,878	457,369	3,120,140
Revenues recognized under ASC 840	3,644,798	3,182,902	406,070
Revenues recognized under ASC 944	195,371	200,768	131,563
Revenues recognized under ASC 320	122,938	137,829	110,934
Total revenues	$ 4,541,985	$ 3,978,868	$ 3,768,707