Comprehensive Income (Loss) and Accumulated Other Comprehensive Income (Details) (USD $)	3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	$ 9,420,000	$ 4,227,000	$ 7,694,000	$ 12,020,000
Other comprehensive income (loss) before reclassifications	5,835,000	3,907,000	7,456,000	(4,059,000)
Amounts reclassified out of AOCI	60,000	(1,476,000)	165,000	(1,303,000)
Other comprehensive income (loss)	5,895,000	2,431,000	7,621,000	(5,362,000)
Balance at the end of the period	15,315,000	6,658,000	15,315,000	6,658,000
Foreign Currency Translation
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	15,810,000	10,141,000	13,538,000	18,107,000
Other comprehensive income (loss) before reclassifications	6,359,000	3,907,000	8,631,000	(4,059,000)
Other comprehensive income (loss)	6,359,000	3,907,000	8,631,000	(4,059,000)
Balance at the end of the period	22,169,000	14,048,000	22,169,000	14,048,000
Defined Benefit Pension Plans, Net of Tax
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	(7,487,000)	(7,980,000)	(7,662,000)	(8,082,000)
Amounts reclassified out of AOCI	121,000	(1,244,000)	296,000	(1,142,000)
Other comprehensive income (loss)	121,000	(1,244,000)	296,000	(1,142,000)
Balance at the end of the period	(7,366,000)	(9,224,000)	(7,366,000)	(9,224,000)
Tax effect of accumulated other comprehensive income (loss)	2,300,000	2,900,000
Post-Retirement Benefit Plans
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	1,748,000	2,066,000	1,818,000	1,995,000
Amounts reclassified out of AOCI	(61,000)	(232,000)	(131,000)	(161,000)
Other comprehensive income (loss)	(61,000)	(232,000)	(131,000)	(161,000)
Balance at the end of the period	1,687,000	1,834,000	1,687,000	1,834,000
Share of Equity Method Investees' Other Comprehensive Income (Loss)
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	(651,000)
Other comprehensive income (loss) before reclassifications	(524,000)		(1,175,000)
Other comprehensive income (loss)	(524,000)		(1,175,000)
Balance at the end of the period	$ (1,175,000)		$ (1,175,000)