Condensed Consolidated Cash Flow Statement (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Jan. 31, 2014	Jan. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Cash provided by (used in) operating activities	$ 18,485	$ (26,288)
Financing activities:
Sold interest in accounts receivable, net of collections	(5,173)	(6,021)
Proceeds from senior secured notes	0	202,000
Proceeds from issuance of capital stock	291,313	0
Proceeds from issuance of senior unsecured notes	300,000	0
Long term debt proceeds	760,000	812,449
Long term debt repayments	(888,656)	(817,594)
Increase in revolver and notes deferred financing costs	(14,034)	(3,793)
Long term intercompany flow - issuance of debt	0	0
Dividend distribution to parent	0
Related party loans	(25,148)	0
Cash provided by (used in) financing activities	418,302	187,041
Investing activities:
Property and equipment additions	(474,158)	(318,558)
Proceeds from disposal of property and equipment	444,570	207,896
Aircraft deposits net of lease inception refunds	(102,388)	(49,517)
Investment in subsidiaries	0
Restricted cash	8,184	2,407
Distributions from equity investments	2,306	745
Dividends received	0
Cash provided by (used in) investing activities	(121,486)	(157,027)
Cash provided by (used in) continuing operations	315,301	3,726
Cash flows provided by (used in) discontinued operations:
Cash flows provided by operating activities	0	1,024
Cash used in financing activities	0	(1,024)
Cash provided by (used in) discontinued operations	0	0
Effect of exchange rate changes on cash and cash equivalents	(21,957)	42
Change in cash and cash equivalents during the period	293,344	3,768
Cash and cash equivalents, beginning of period	123,801	55,639
Cash and cash equivalents, end of period	417,145	59,407
Parent
Condensed Financial Statements, Captions [Line Items]
Cash provided by (used in) operating activities	(1,783)	0
Financing activities:
Sold interest in accounts receivable, net of collections	0	0
Proceeds from senior secured notes		0
Proceeds from issuance of capital stock	291,313
Proceeds from issuance of senior unsecured notes	0
Long term debt proceeds	0	0
Long term debt repayments	0	0
Increase in revolver and notes deferred financing costs	0	0
Long term intercompany flow - issuance of debt	(35,000)	0
Dividend distribution to parent	0
Related party loans	0
Cash provided by (used in) financing activities	256,313	0
Investing activities:
Property and equipment additions	0	0
Proceeds from disposal of property and equipment	0	0
Aircraft deposits net of lease inception refunds	0	0
Investment in subsidiaries	(254,520)
Restricted cash	0	0
Distributions from equity investments	0	0
Dividends received	0
Cash provided by (used in) investing activities	(254,520)	0
Cash provided by (used in) continuing operations	10	0
Cash flows provided by (used in) discontinued operations:
Cash flows provided by operating activities		0
Cash used in financing activities		0
Cash provided by (used in) discontinued operations		0
Effect of exchange rate changes on cash and cash equivalents	0	0
Change in cash and cash equivalents during the period	10	0
Cash and cash equivalents, beginning of period	0	0
Cash and cash equivalents, end of period	10	0
SubParent
Condensed Financial Statements, Captions [Line Items]
Cash provided by (used in) operating activities	5	(5)
Financing activities:
Sold interest in accounts receivable, net of collections	0	0
Proceeds from senior secured notes		0
Proceeds from issuance of capital stock	254,520
Proceeds from issuance of senior unsecured notes	0
Long term debt proceeds	0	0
Long term debt repayments	0	0
Increase in revolver and notes deferred financing costs	0	0
Long term intercompany flow - issuance of debt	0	0
Dividend distribution to parent	0
Related party loans	(25,148)
Cash provided by (used in) financing activities	229,372	0
Investing activities:
Property and equipment additions	0	0
Proceeds from disposal of property and equipment	0	0
Aircraft deposits net of lease inception refunds	0	0
Investment in subsidiaries	(314,520)
Restricted cash	0	0
Distributions from equity investments	0	0
Dividends received	85,148
Cash provided by (used in) investing activities	(229,372)	0
Cash provided by (used in) continuing operations	5	(5)
Cash flows provided by (used in) discontinued operations:
Cash flows provided by operating activities		0
Cash used in financing activities		0
Cash provided by (used in) discontinued operations		0
Effect of exchange rate changes on cash and cash equivalents	0	0
Change in cash and cash equivalents during the period	5	(5)
Cash and cash equivalents, beginning of period	87	92
Cash and cash equivalents, end of period	92	87
Issuer
Condensed Financial Statements, Captions [Line Items]
Cash provided by (used in) operating activities	(137,987)	(128,195)
Financing activities:
Sold interest in accounts receivable, net of collections	0	0
Proceeds from senior secured notes		202,000
Proceeds from issuance of capital stock	254,520
Proceeds from issuance of senior unsecured notes	300,000
Long term debt proceeds	710,000	752,144
Long term debt repayments	(760,000)	(805,000)
Increase in revolver and notes deferred financing costs	(14,034)	(3,793)
Long term intercompany flow - issuance of debt	(144,897)	0
Dividend distribution to parent	0
Related party loans	0
Cash provided by (used in) financing activities	345,589	145,351
Investing activities:
Property and equipment additions	0	0
Proceeds from disposal of property and equipment	0	0
Aircraft deposits net of lease inception refunds	0	0
Investment in subsidiaries	0
Restricted cash	0	0
Distributions from equity investments	0	0
Dividends received	195
Cash provided by (used in) investing activities	195	0
Cash provided by (used in) continuing operations	207,797	17,156
Cash flows provided by (used in) discontinued operations:
Cash flows provided by operating activities		0
Cash used in financing activities		0
Cash provided by (used in) discontinued operations		0
Effect of exchange rate changes on cash and cash equivalents	0	0
Change in cash and cash equivalents during the period	207,797	17,156
Cash and cash equivalents, beginning of period	3,478	(6,771)
Cash and cash equivalents, end of period	211,275	10,385
Guarantor
Condensed Financial Statements, Captions [Line Items]
Cash provided by (used in) operating activities	111,271	25,640
Financing activities:
Sold interest in accounts receivable, net of collections	0	0
Proceeds from senior secured notes		202,000
Proceeds from issuance of capital stock	314,520
Proceeds from issuance of senior unsecured notes	300,000
Long term debt proceeds	760,000	812,449
Long term debt repayments	(888,656)	(817,594)
Increase in revolver and notes deferred financing costs	(14,034)	(3,793)
Long term intercompany flow - issuance of debt	12,969	(1,821)
Dividend distribution to parent	(85,148)
Related party loans	0
Cash provided by (used in) financing activities	399,651	191,241
Investing activities:
Property and equipment additions	(439,898)	(298,556)
Proceeds from disposal of property and equipment	444,398	207,863
Aircraft deposits net of lease inception refunds	(102,388)	(49,517)
Investment in subsidiaries	0
Restricted cash	1,223	(1,364)
Distributions from equity investments	629	745
Dividends received	0
Cash provided by (used in) investing activities	(96,036)	(140,829)
Cash provided by (used in) continuing operations	414,886	76,052
Cash flows provided by (used in) discontinued operations:
Cash flows provided by operating activities		1,024
Cash used in financing activities		(1,024)
Cash provided by (used in) discontinued operations		0
Effect of exchange rate changes on cash and cash equivalents	(21,128)	(715)
Change in cash and cash equivalents during the period	393,758	75,337
Cash and cash equivalents, beginning of period	136,835	41,228
Cash and cash equivalents, end of period	530,593	116,565
Non-guarantor
Condensed Financial Statements, Captions [Line Items]
Cash provided by (used in) operating activities	(89,702)	(51,923)
Financing activities:
Sold interest in accounts receivable, net of collections	(5,173)	(6,021)
Proceeds from senior secured notes		0
Proceeds from issuance of capital stock	0
Proceeds from issuance of senior unsecured notes	0
Long term debt proceeds	0	0
Long term debt repayments	0	0
Increase in revolver and notes deferred financing costs	0	0
Long term intercompany flow - issuance of debt	22,031	1,821
Dividend distribution to parent	0
Related party loans	0
Cash provided by (used in) financing activities	16,858	(4,200)
Investing activities:
Property and equipment additions	(35,566)	(20,002)
Proceeds from disposal of property and equipment	172	33
Aircraft deposits net of lease inception refunds	0	0
Investment in subsidiaries	0
Restricted cash	6,961	3,771
Distributions from equity investments	1,677	0
Dividends received	0
Cash provided by (used in) investing activities	(26,756)	(16,198)
Cash provided by (used in) continuing operations	(99,600)	(72,321)
Cash flows provided by (used in) discontinued operations:
Cash flows provided by operating activities		0
Cash used in financing activities		0
Cash provided by (used in) discontinued operations		0
Effect of exchange rate changes on cash and cash equivalents	(829)	757
Change in cash and cash equivalents during the period	(100,429)	(71,564)
Cash and cash equivalents, beginning of period	(13,121)	14,319
Cash and cash equivalents, end of period	(113,550)	(57,245)
Eliminations
Condensed Financial Statements, Captions [Line Items]
Cash provided by (used in) operating activities	136,681	128,195
Financing activities:
Sold interest in accounts receivable, net of collections	0	0
Proceeds from senior secured notes		(202,000)
Proceeds from issuance of capital stock	(823,560)
Proceeds from issuance of senior unsecured notes	(300,000)
Long term debt proceeds	(710,000)	(752,144)
Long term debt repayments	760,000	805,000
Increase in revolver and notes deferred financing costs	14,034	3,793
Long term intercompany flow - issuance of debt	144,897	0
Dividend distribution to parent	85,148
Related party loans	0
Cash provided by (used in) financing activities	(829,481)	(145,351)
Investing activities:
Property and equipment additions	1,306	0
Proceeds from disposal of property and equipment	0	0
Aircraft deposits net of lease inception refunds	0	0
Investment in subsidiaries	569,040
Restricted cash	0	0
Distributions from equity investments	0	0
Dividends received	(85,343)
Cash provided by (used in) investing activities	485,003	0
Cash provided by (used in) continuing operations	(207,797)	(17,156)
Cash flows provided by (used in) discontinued operations:
Cash flows provided by operating activities		0
Cash used in financing activities		0
Cash provided by (used in) discontinued operations		0
Effect of exchange rate changes on cash and cash equivalents	0	0
Change in cash and cash equivalents during the period	(207,797)	(17,156)
Cash and cash equivalents, beginning of period	(3,478)	6,771
Cash and cash equivalents, end of period	$ (211,275)	$ (10,385)