SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION BS (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2012	Mar. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 159,992	$ 215,623	$ 227,250	$ 261,550
Accounts Receivable, Net, Current	268,656	262,781
Inventories	157,946	153,969
Assets held for sale	13,627	8,290
Prepaid expenses and other current assets	32,266	35,095
Total current assets	632,487	675,758
Intercompany investment	0	0
Investment in unconsolidated affiliates	276,997	272,123
Intercompany notes receivable	0	0
Total property and equipment, at cost	2,570,680	2,414,647
Less - Accumulated depreciation and amortization	(507,390)	(493,575)
Property, Plant and Equipment, Net	2,063,290	1,921,072
Goodwill	28,845	28,897
Other assets	56,868	52,842
Total assets	3,058,487	2,950,692
Accounts payable	73,138	69,821
Accrued Liabilities, Current	128,824	147,681
Current deferred taxes	3,911	0
Short-term borrowings and current maturities of long-term debt	6,950	22,323
Total current liabilities	212,823	239,825
Long-term debt, less current maturities	882,823	764,946
Intercompany notes payable	0	0
Accrued pension liabilities	121,476	126,647
Other liabilities and deferred credits	53,532	57,196
Deferred taxes	159,926	151,121
Common stock	369	367
Additional paid-in capital	737,070	731,883
Retained earnings	1,112,644	1,094,803
Accumulated other comprehensive income (loss)	(204,242)	(199,683)
Treasury shares	(26,304)	(26,304)
Stockholders' equity	1,619,537	1,601,066
Noncontrolling interests	8,370	9,891
Total stockholders' investment	1,627,907	1,610,957
Total liabilities and stockholders' investment	3,058,487	2,950,692
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	861	31,853	54,156	76,609
Accounts Receivable, Net, Current	16,918	18,498
Inventories	0	0
Assets held for sale	0	0
Prepaid expenses and other current assets	2,547	16,071
Total current assets	20,326	66,422
Intercompany investment	1,198,003	1,163,935
Investment in unconsolidated affiliates	0	0
Intercompany notes receivable	1,526,557	1,401,680
Total property and equipment, at cost	37,629	32,249
Less - Accumulated depreciation and amortization	(11,359)	(10,680)
Property, Plant and Equipment, Net	26,270	21,569
Goodwill	0	0
Other assets	41,464	40,877
Total assets	2,812,620	2,694,483
Accounts payable	5,311	4,049
Accrued Liabilities, Current	15,015	29,534
Current deferred taxes	(4,850)	(4,184)
Short-term borrowings and current maturities of long-term debt	5,766	21,875
Total current liabilities	21,242	51,274
Long-term debt, less current maturities	882,823	764,946
Intercompany notes payable	0	0
Accrued pension liabilities	0	0
Other liabilities and deferred credits	7,946	10,761
Deferred taxes	137,311	128,153
Common stock	369	367
Additional paid-in capital	737,070	731,883
Retained earnings	1,112,644	1,094,803
Accumulated other comprehensive income (loss)	(61,972)	(62,892)
Treasury shares	(26,304)	(26,304)
Stockholders' equity	1,761,807	1,737,857
Noncontrolling interests	1,491	1,492
Total stockholders' investment	1,763,298	1,739,349
Total liabilities and stockholders' investment	2,812,620	2,694,483
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	3,259	5,370	4,061	3,155
Accounts Receivable, Net, Current	65,990	80,615
Inventories	52,481	51,970
Assets held for sale	5,800	1,268
Prepaid expenses and other current assets	9,695	12,415
Total current assets	137,225	151,638
Intercompany investment	111,435	111,435
Investment in unconsolidated affiliates	150	150
Intercompany notes receivable	0	0
Total property and equipment, at cost	1,363,696	1,219,438
Less - Accumulated depreciation and amortization	(208,841)	(205,746)
Property, Plant and Equipment, Net	1,154,855	1,013,692
Goodwill	4,755	4,756
Other assets	1,292	1,341
Total assets	1,409,712	1,283,012
Accounts payable	35,004	44,017
Accrued Liabilities, Current	21,177	22,404
Current deferred taxes	(230)	115
Short-term borrowings and current maturities of long-term debt	0	0
Total current liabilities	55,951	66,536
Long-term debt, less current maturities	0	0
Intercompany notes payable	578,726	463,184
Accrued pension liabilities	0	0
Other liabilities and deferred credits	7,959	8,530
Deferred taxes	8,499	8,328
Common stock	4,996	4,996
Additional paid-in capital	9,291	9,291
Retained earnings	744,290	722,147
Accumulated other comprehensive income (loss)	0	0
Treasury shares	0	0
Stockholders' equity	758,577	736,434
Noncontrolling interests	0	0
Total stockholders' investment	758,577	736,434
Total liabilities and stockholders' investment	1,409,712	1,283,012
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	155,872	178,400	169,033	181,786
Accounts Receivable, Net, Current	233,727	246,612
Inventories	105,465	101,999
Assets held for sale	7,827	7,022
Prepaid expenses and other current assets	21,493	23,263
Total current assets	524,384	557,296
Intercompany investment	0	0
Investment in unconsolidated affiliates	276,847	271,973
Intercompany notes receivable	0	0
Total property and equipment, at cost	1,169,355	1,162,960
Less - Accumulated depreciation and amortization	(287,190)	(277,149)
Property, Plant and Equipment, Net	882,165	885,811
Goodwill	24,090	24,141
Other assets	152,280	149,544
Total assets	1,859,766	1,888,765
Accounts payable	78,726	101,021
Accrued Liabilities, Current	99,073	115,112
Current deferred taxes	8,991	4,069
Short-term borrowings and current maturities of long-term debt	1,184	448
Total current liabilities	187,974	220,650
Long-term debt, less current maturities	0	0
Intercompany notes payable	972,295	963,687
Accrued pension liabilities	121,476	126,647
Other liabilities and deferred credits	178,279	178,525
Deferred taxes	14,116	14,640
Common stock	22,876	22,876
Additional paid-in capital	270,905	270,905
Retained earnings	72,209	62,602
Accumulated other comprehensive income (loss)	12,757	19,834
Treasury shares	0	0
Stockholders' equity	378,747	376,217
Noncontrolling interests	6,879	8,399
Total stockholders' investment	385,626	384,616
Total liabilities and stockholders' investment	1,859,766	1,888,765
Consolidations, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	0	0
Accounts Receivable, Net, Current	(47,979)	(82,944)
Inventories	0	0
Assets held for sale	0	0
Prepaid expenses and other current assets	(1,469)	(16,654)
Total current assets	(49,448)	(99,598)
Intercompany investment	(1,309,438)	(1,275,370)
Investment in unconsolidated affiliates	0	0
Intercompany notes receivable	(1,526,557)	(1,401,680)
Total property and equipment, at cost	0	0
Less - Accumulated depreciation and amortization	0	0
Property, Plant and Equipment, Net	0	0
Goodwill	0	0
Other assets	(138,168)	(138,920)
Total assets	(3,023,611)	(2,915,568)
Accounts payable	(45,903)	(79,266)
Accrued Liabilities, Current	(6,441)	(19,369)
Current deferred taxes	0	0
Short-term borrowings and current maturities of long-term debt	0	0
Total current liabilities	(52,344)	(98,635)
Long-term debt, less current maturities	0	0
Intercompany notes payable	(1,551,021)	(1,426,871)
Accrued pension liabilities	0	0
Other liabilities and deferred credits	(140,652)	(140,620)
Deferred taxes	0	0
Common stock	(27,872)	(27,872)
Additional paid-in capital	(280,196)	(280,196)
Retained earnings	(816,499)	(784,749)
Accumulated other comprehensive income (loss)	(155,027)	(156,625)
Treasury shares	0	0
Stockholders' equity	(1,279,594)	(1,249,442)
Noncontrolling interests	0	0
Total stockholders' investment	(1,279,594)	(1,249,442)
Total liabilities and stockholders' investment	(3,023,611)	(2,915,568)
Land and Building [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	109,125	108,593
Land and Building [Member] | Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	977	939
Land and Building [Member] | Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	48,936	48,907
Land and Building [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	59,212	58,747
Land and Building [Member] | Consolidations, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	0	0
Aircraft And Equipment [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	2,461,555	2,306,054
Aircraft And Equipment [Member] | Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	36,652	31,310
Aircraft And Equipment [Member] | Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	1,314,760	1,170,531
Aircraft And Equipment [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	1,110,143	1,104,213
Aircraft And Equipment [Member] | Consolidations, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	$ 0	$ 0