Summary Financial Information (Consolidated Statements of Cash Flows ) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Operating activities:
Net cash (used for) provided by operating activities	$ 1,709	$ 7,574
INVESTING ACTIVITIES:
Proceeds from sale of marketable securities	3,724	3,101
Purchases of marketable securities	(2,597)	(1,936)
Capital expenditures	(8,033)	(4,080)
Proceeds from sale of assets	0	1,482
Purchase of business	(5,847)	0
Intercompany transactions	0
Net cash used for investing activities	(12,753)	(1,433)
FINANCING ACTIVITIES:
Net payments under lines-of-credit	0	(51)
Proceeds from exercise of stock options	838	219
Repayment of debt	(295)	(393)
Change in ESOP guarantee	206	213
Other		(180)
Net cash provided by (used for) financing activities	749	(12)
Effect of exchange rate changes on cash	454	(675)
Net change in cash and cash equivalents	(9,841)	5,454
Cash and cash equivalents at beginning of period	121,660	89,473
Cash and cash equivalents at end of period	111,819	94,927
Parent
Operating activities:
Net cash (used for) provided by operating activities	10,999	6,557
INVESTING ACTIVITIES:
Proceeds from sale of marketable securities		0
Purchases of marketable securities		0
Capital expenditures	(1,318)	(3,354)
Proceeds from sale of assets		0
Intercompany transactions	(13,303)
Net cash used for investing activities	(14,621)	(3,354)
FINANCING ACTIVITIES:
Proceeds from exercise of stock options	838	219
Change in ESOP guarantee	206
Other		213
Net cash provided by (used for) financing activities	1,044	432
Net change in cash and cash equivalents	(2,578)	3,635
Cash and cash equivalents at beginning of period	79,412	55,958
Cash and cash equivalents at end of period	76,834	59,593
Guarantors
Operating activities:
Net cash (used for) provided by operating activities	1,267	(1,276)
INVESTING ACTIVITIES:
Proceeds from sale of marketable securities		0
Purchases of marketable securities		0
Capital expenditures	(1,116)	(211)
Proceeds from sale of assets		1,482
Net cash used for investing activities	(1,116)	1,271
FINANCING ACTIVITIES:
Repayment of debt	(151)
Net cash provided by (used for) financing activities	(151)
Net change in cash and cash equivalents		(5)
Cash and cash equivalents at beginning of period	0	5
Cash and cash equivalents at end of period	0	0
Non Guarantors
Operating activities:
Net cash (used for) provided by operating activities	(10,557)	2,293
INVESTING ACTIVITIES:
Proceeds from sale of marketable securities	3,724	3,101
Purchases of marketable securities	(2,597)	(1,936)
Capital expenditures	(5,599)	(515)
Proceeds from sale of assets		0
Purchase of business	(5,847)
Intercompany transactions	13,303
Net cash used for investing activities	2,984	650
FINANCING ACTIVITIES:
Net payments under lines-of-credit		(51)
Proceeds from exercise of stock options		0
Repayment of debt	(144)
Other		(393)
Net cash provided by (used for) financing activities	(144)	(444)
Effect of exchange rate changes on cash	454	(675)
Net change in cash and cash equivalents	(7,263)	1,824
Cash and cash equivalents at beginning of period	42,248	33,510
Cash and cash equivalents at end of period	34,985	35,334
Eliminations
INVESTING ACTIVITIES:
Purchase of business	0
FINANCING ACTIVITIES:
Proceeds from exercise of stock options	$ 0