SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION BS (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2013	Mar. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 133,804	$ 204,341	$ 159,992	$ 215,623
Accounts Receivable, Net, Current	310,598	297,443
Inventories	150,913	137,463
Assets held for sale	30,293	29,276
Prepaid expenses and other current assets	54,787	53,084
Total current assets	680,395	721,607
Intercompany investment	0	0
Investment in unconsolidated affiliates	265,955	262,615
Intercompany notes receivable	0	0
Total property and equipment, at cost	2,978,744	2,792,123
Less - Accumulated depreciation and amortization	(536,362)	(523,372)
Property, Plant and Equipment, Net	2,442,382	2,268,751
Goodwill	57,771	56,680
Other assets	94,215	88,604
Total assets	3,540,718	3,398,257
Accounts payable	102,278	89,818
Accrued Liabilities, Current	187,790	204,498
Current deferred taxes	14,090	12,372
Short-term borrowings and current maturities of long-term debt	13,851	14,207
Deferred sale leaseback advance	152,347	136,930
Total current liabilities	470,356	457,825
Long-term debt, less current maturities	941,257	827,095
Intercompany notes payable	0	0
Accrued pension liabilities	82,365	86,823
Other liabilities and deferred credits	59,876	78,126
Deferred taxes	179,232	169,519
Temporary equity	24,245	22,283
Common stock	374	373
Additional paid-in capital	767,918	762,813
Retained earnings	1,277,976	1,245,220
Accumulated other comprehensive income (loss)	(147,298)	(156,506)
Treasury shares	(124,122)	(103,965)
Stockholders' equity	1,774,848	1,747,935
Noncontrolling interests	8,539	8,651
Total stockholders' investment	1,783,387	1,756,586
Total liabilities and stockholders' investment	3,540,718	3,398,257
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	6,660	4,640	861	31,853
Accounts Receivable, Net, Current	28,717	32,280
Inventories	0	0
Assets held for sale	0	0
Prepaid expenses and other current assets	3,017	3,882
Total current assets	38,394	40,802
Intercompany investment	1,274,404	1,273,337
Investment in unconsolidated affiliates	0	0
Intercompany notes receivable	1,396,993	1,286,354
Total property and equipment, at cost	76,290	65,071
Less - Accumulated depreciation and amortization	(12,897)	(13,057)
Property, Plant and Equipment, Net	63,393	52,014
Goodwill	0	0
Other assets	200,034	204,679
Total assets	2,973,218	2,857,186
Accounts payable	10,930	8,298
Accrued Liabilities, Current	15,991	36,442
Current deferred taxes	(4,728)	(7,640)
Short-term borrowings and current maturities of long-term debt	5,679	4,543
Deferred sale leaseback advance	0	0
Total current liabilities	27,872	41,643
Long-term debt, less current maturities	921,494	805,965
Intercompany notes payable	0	0
Accrued pension liabilities	0	0
Other liabilities and deferred credits	11,265	13,750
Deferred taxes	150,507	144,461
Temporary equity	0	0
Common stock	374	373
Additional paid-in capital	767,918	762,813
Retained earnings	1,277,976	1,245,220
Accumulated other comprehensive income (loss)	(61,755)	(54,719)
Treasury shares	(124,122)	(103,965)
Stockholders' equity	1,860,391	1,849,722
Noncontrolling interests	1,689	1,645
Total stockholders' investment	1,862,080	1,851,367
Total liabilities and stockholders' investment	2,973,218	2,857,186
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	3,259	5,370
Accounts Receivable, Net, Current	190,627	104,155
Inventories	42,622	40,864
Assets held for sale	10,734	8,505
Prepaid expenses and other current assets	2,691	3,258
Total current assets	246,674	156,782
Intercompany investment	111,435	111,435
Investment in unconsolidated affiliates	0	0
Intercompany notes receivable	0	0
Total property and equipment, at cost	1,405,280	1,406,625
Less - Accumulated depreciation and amortization	(216,061)	(211,385)
Property, Plant and Equipment, Net	1,189,219	1,195,240
Goodwill	4,755	4,755
Other assets	1,363	1,462
Total assets	1,553,446	1,469,674
Accounts payable	81,352	67,728
Accrued Liabilities, Current	28,314	32,084
Current deferred taxes	(1,409)	(1,342)
Short-term borrowings and current maturities of long-term debt	0	0
Deferred sale leaseback advance	152,347	136,930
Total current liabilities	260,604	235,400
Long-term debt, less current maturities	0	0
Intercompany notes payable	425,169	378,983
Accrued pension liabilities	0	0
Other liabilities and deferred credits	22,539	37,876
Deferred taxes	9,614	9,472
Temporary equity	0	0
Common stock	4,996	4,996
Additional paid-in capital	9,291	9,291
Retained earnings	821,233	793,656
Accumulated other comprehensive income (loss)	0	0
Treasury shares	0	0
Stockholders' equity	835,520	807,943
Noncontrolling interests	0	0
Total stockholders' investment	835,520	807,943
Total liabilities and stockholders' investment	1,553,446	1,469,674
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	129,008	200,147	155,872	178,400
Accounts Receivable, Net, Current	337,076	310,288
Inventories	108,291	96,599
Assets held for sale	19,559	20,771
Prepaid expenses and other current assets	49,079	45,944
Total current assets	643,013	673,749
Intercompany investment	0	0
Investment in unconsolidated affiliates	265,955	262,615
Intercompany notes receivable	0	0
Total property and equipment, at cost	1,497,174	1,320,427
Less - Accumulated depreciation and amortization	(307,404)	(298,930)
Property, Plant and Equipment, Net	1,189,770	1,021,497
Goodwill	53,016	51,925
Other assets	53,045	50,392
Total assets	2,204,799	2,060,178
Accounts payable	173,202	157,297
Accrued Liabilities, Current	150,319	141,423
Current deferred taxes	20,227	21,354
Short-term borrowings and current maturities of long-term debt	8,172	9,664
Deferred sale leaseback advance	0	0
Total current liabilities	351,920	329,738
Long-term debt, less current maturities	19,763	21,130
Intercompany notes payable	1,209,665	1,076,292
Accrued pension liabilities	82,365	86,823
Other liabilities and deferred credits	26,072	26,500
Deferred taxes	19,111	15,586
Temporary equity	24,245	22,283
Common stock	22,876	22,876
Additional paid-in capital	270,905	270,905
Retained earnings	186,574	177,159
Accumulated other comprehensive income (loss)	(15,547)	3,880
Treasury shares	0	0
Stockholders' equity	464,808	474,820
Noncontrolling interests	6,850	7,006
Total stockholders' investment	471,658	481,826
Total liabilities and stockholders' investment	2,204,799	2,060,178
Consolidations, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	(1,864)	(446)	0	0
Accounts Receivable, Net, Current	(245,822)	(149,280)
Inventories	0	0
Assets held for sale	0	0
Prepaid expenses and other current assets	0	0
Total current assets	(247,686)	(149,726)
Intercompany investment	(1,385,839)	(1,384,772)
Investment in unconsolidated affiliates	0	0
Intercompany notes receivable	(1,396,993)	(1,286,354)
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	(160,227)	(167,929)
Total assets	(3,190,745)	(2,988,781)
Accounts payable	(163,206)	(143,505)
Accrued Liabilities, Current	(6,834)	(5,451)
Current deferred taxes	0	0
Short-term borrowings and current maturities of long-term debt	0	0
Deferred sale leaseback advance	0	0
Total current liabilities	(170,040)	(148,956)
Long-term debt, less current maturities	0	0
Intercompany notes payable	(1,634,834)	(1,455,275)
Accrued pension liabilities	0	0
Other liabilities and deferred credits	0	0
Deferred taxes	0	0
Temporary equity	0	0
Common stock	(27,872)	(27,872)
Additional paid-in capital	(280,196)	(280,196)
Retained earnings	(1,007,807)	(970,815)
Accumulated other comprehensive income (loss)	(69,996)	(105,667)
Treasury shares	0	0
Stockholders' equity	(1,385,871)	(1,384,550)
Noncontrolling interests	0	0
Total stockholders' investment	(1,385,871)	(1,384,550)
Total liabilities and stockholders' investment	(3,190,745)	(2,988,781)
Land and Building [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	149,829	145,973
Land and Building [Member] | Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	977	977
Land and Building [Member] | Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	48,789	49,499
Land and Building [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	100,063	95,497
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	2,828,915	2,646,150
Aircraft And Equipment [Member] | Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	75,313	64,094
Aircraft And Equipment [Member] | Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	1,356,491	1,357,126
Aircraft And Equipment [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	1,397,111	1,224,930
Aircraft And Equipment [Member] | Consolidations, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Total property and equipment, at cost	$ 0	$ 0