Summary Financial Information (Consolidated Statements of Cash Flows ) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Operating activities:
Net cash provided by (used for) operating activities	$ 69,661	$ 60,450	$ 52,645
Investing activities:
Proceeds from sales of marketable securities	653	12,336	5,869
Purchases of marketable securities	(327)	(1,571)	(4,311)
Capital expenditures	(14,515)	(14,368)	(22,320)
Financing activities:
Proceeds from the issuance of common stock	6,332	50,439	242
Net borrowings (repayments) under lines of credit	0	(155,000)	154,057
Repayment of debt	(60,144)	(125,730)	(13,187)
Fees related to debt repricing/refinancing and equity offerings	(619)	(19,409)	0
Other	(1,413)	(1,265)	(897)
Net cash (used for) provided by financing activities	(59,502)	190,121	137,003
Effect of exchange rate changes on cash	7,569	(544)	2,128
Net change in cash and cash equivalents	(14,570)	25,988	(11,453)
Cash and cash equivalents at beginning of year	77,591	51,603	63,056
Cash and cash equivalents at end of year	$ 63,021	$ 77,591	$ 51,603