Comprehensive Income (Loss) and Accumulated Other Comprehensive Income (Details) (USD $)	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	$ 17,583,000	$ 9,420,000	$ 18,184,000	$ 7,694,000
Other comprehensive income (loss) before reclassifications	(10,677,000)	5,835,000	(11,286,000)	7,456,000
Amounts reclassified out of AOCI	29,000	60,000	37,000	165,000
Other comprehensive income (loss)	(10,648,000)	5,895,000	(11,249,000)	7,621,000
Balance at the end of the period	6,935,000	15,315,000	6,935,000	15,315,000
Foreign Currency Translation
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	22,235,000	15,810,000	23,335,000	13,538,000
Other comprehensive income (loss) before reclassifications	(13,659,000)	6,359,000	(14,759,000)	8,631,000
Other comprehensive income (loss)	(13,659,000)	6,359,000	(14,759,000)	8,631,000
Balance at the end of the period	8,576,000	22,169,000	8,576,000	22,169,000
Defined Benefit Pension Plans, Net of Tax
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	(7,326,000)	(7,487,000)	(7,386,000)	(7,662,000)
Amounts reclassified out of AOCI	81,000	121,000	141,000	296,000
Other comprehensive income (loss)	81,000	121,000	141,000	296,000
Balance at the end of the period	(7,245,000)	(7,366,000)	(7,245,000)	(7,366,000)
Accumulated tax expense (benefit)	(2,200,000)	(2,300,000)	(2,200,000)	(2,300,000)
Post-Retirement Benefit Plans
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	1,412,000	1,748,000	1,464,000	1,818,000
Amounts reclassified out of AOCI	(52,000)	(61,000)	(104,000)	(131,000)
Other comprehensive income (loss)	(52,000)	(61,000)	(104,000)	(131,000)
Balance at the end of the period	1,360,000	1,687,000	1,360,000	1,687,000
Ownership Share of Equity Method Investees’ Other Comprehensive Income (Loss)
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	1,262,000	(651,000)	771,000	0
Other comprehensive income (loss) before reclassifications	2,982,000	(524,000)	3,473,000	(1,175,000)
Other comprehensive income (loss)	2,982,000	(524,000)	3,473,000	(1,175,000)
Balance at the end of the period	$ 4,244,000	$ (1,175,000)	$ 4,244,000	$ (1,175,000)