Revenue Recognition (Revenue Reconciliation) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total revenues	$ 241,414	$ 270,615	$ 734,751	$ 785,214
Cost of sales	102,179	122,941	317,421	349,966
Total operating expenses	61,694	63,784	196,378	196,678
Income before income taxes	50,996	57,639	140,975	159,648
Provision (benefit) for income taxes	12,829	(257,154)	37,501	(219,609)
Net income	38,167	$ 314,793	103,474	$ 379,257
Impact of Change | New Revenue Standard Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total revenues	13,618		(8,492)
Cost of sales	5,140		(3,256)
Total operating expenses	391		(188)
Income before income taxes	8,087		(5,048)
Provision (benefit) for income taxes	2,038		(1,714)
Net income	6,049		(3,334)
Without Adoption of ASC 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total revenues	255,032		726,259
Cost of sales	107,319		314,165
Total operating expenses	62,085		196,190
Income before income taxes	59,083		135,927
Provision (benefit) for income taxes	14,867		35,787
Net income	$ 44,216		$ 100,140