Organization and Significant Accounting Policies - OCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at the beginning of the period	$ (41,812)	$ (31,425)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	(41,217)	5,708
Other Comprehensive Income, Other, Net of Tax	(2,420)	(4,679)
Other comprehensive income (loss)	(38,797)	10,387	$ 2,629
Balance at the end of the period	(3,015)	(41,812)	(31,425)
Foreign currency translation gains (losses), net of tax
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at the beginning of the period	(25,556)	(10,272)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	(35,054)	15,284	(1,860)
Other comprehensive income (loss)	(35,054)	15,284
Balance at the end of the period	9,498	(25,556)	(10,272)
Defined benefit post-retirement plan adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at the beginning of the period	1,134	1,114
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	255	(228)
Amounts reclassified out of OCI	(255)	20	(45)
Other Comprehensive Income, Other, Net of Tax	0	208
Other comprehensive income (loss)	(255)	(20)
Balance at the end of the period	879	1,134	1,114
Defined benefit pension plans, net of tax
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at the beginning of the period	(14,998)	(15,161)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	(167)	536
Amounts reclassified out of OCI	167	163	5,202
Other Comprehensive Income, Other, Net of Tax	0	(699)
Other comprehensive income (loss)	167	(163)
Balance at the end of the period	(14,831)	(14,998)	(15,161)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	0	0
Defined Benefit Pension Plans, tax benefit	(400)	700
Other Comprehensive Income (Loss), Tax	2,300	2,700	2,000
Equity interest in investee's other comprehensive loss
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at the beginning of the period	(5,299)	(6,739)
Amounts reclassified out of OCI	5,584	1,440	(8,276)
Other Comprehensive Income, Other, Net of Tax	0	0
Other comprehensive income (loss)	(5,584)	(1,440)
Balance at the end of the period	285	(5,299)	(6,739)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at the beginning of the period	2,907	(367)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	667	8,444
Other Comprehensive Income, Other, Net of Tax	(2,420)	5,170
Other comprehensive income (loss)	1,753	(3,274)	1,370
Balance at the end of the period	$ 1,154	$ 2,907	$ (367)