Summary Financial Information (Consolidated Statements of Cash Flows ) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Operating activities:
Net cash provided by (used for) operating activities	$ 79,499	$ 69,661	$ 60,450
Investing activities:
Proceeds from sale of marketable securities	3,266	653	12,336
Purchases of marketable securities	(2,604)	(327)	(1,571)
Capital expenditures	(12,288)	(14,515)	(14,368)
Financing activities:
Proceeds from issuance of common stock	4,152	6,332	50,439
Net borrowings under line-of-credit agreements	0	0	(155,000)
Repayment of debt	(65,088)	(60,144)	(125,730)
Fees related to debt repricing/refinancing and equity offerings	0	(619)	(19,409)
Other	(2,190)	(1,413)	(1,265)
Net cash (used for) provided by financing activities	(67,778)	(59,502)	190,709
Effect of exchange rate changes on cash	(6,429)	7,569	(544)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 71,343	$ 63,565	$ 78,429	$ 51,853