Organization and Significant Accounting Policies - OCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Accumulated other comprehensive income (loss)
Balance at the beginning of the period	$ (28,796)	$ 18,184
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	(213)	47,221
Other Comprehensive Income, Other, Net of Tax	(2,842)	241
Other comprehensive income (loss)	2,629	46,980	$ (10,490)
Balance at the end of the period	(31,425)	(28,796)	18,184
Foreign currency translation gains (losses), net of tax
Accumulated other comprehensive income (loss)
Balance at the beginning of the period	(12,132)	23,335
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	(1,860)	35,467	(9,797)
Other Comprehensive Income, Other, Net of Tax	0	0
Other comprehensive income (loss)	(1,860)	35,467
Balance at the end of the period	(10,272)	(12,132)	23,335
Defined benefit post-retirement plan adjustments
Accumulated other comprehensive income (loss)
Balance at the beginning of the period	1,159	1,464
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	(146)	119
Amounts reclassified out of OCI	(45)	305	(354)
Other Comprehensive Income, Other, Net of Tax	191	186
Other comprehensive income (loss)	(45)	305
Balance at the end of the period	1,114	1,159	1,464
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated other comprehensive income (loss)
Balance at the beginning of the period	(20,363)	(7,386)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	(3,865)	13,404
Amounts reclassified out of OCI	5,202	12,977	276
Other Comprehensive Income, Other, Net of Tax	(1,337)	(427)
Other comprehensive income (loss)	5,202	12,977
Balance at the end of the period	(15,161)	(20,363)	(7,386)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	0	(300)
Defined Benefit Pension Plans, tax benefit	(300)	100
Other Comprehensive Income (Loss), Tax	2,000	2,300	2,200
Equity interest in investee's other comprehensive loss
Accumulated other comprehensive income (loss)
Balance at the beginning of the period	1,537	771
Amounts reclassified out of OCI	(8,276)	(766)	771
Other Comprehensive Income, Other, Net of Tax	0	0
Other comprehensive income (loss)	8,276	(766)
Balance at the end of the period	(6,739)	1,537	771
Forward Contracts
Accumulated other comprehensive income (loss)
Balance at the beginning of the period	1,003	0
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	2,618	1,003
Other Comprehensive Income, Other, Net of Tax	(3,988)	0
Other comprehensive income (loss)	1,370	(1,003)	0
Balance at the end of the period	$ (367)	$ 1,003	$ 0