Condensed Consolidating Financial Information - Guarantor Subsidiaries - Condensed Consolidating Statements of Cash Flows (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities	$ 6,122		$ 30,103
Investing activities:
Purchase of property and equipment	(38,746)		(24,936)
Proceeds from asset dispositions	2,994		200
Purchase of short-term investments	(140,551)		(70,608)
Payments of deposits on aircraft			(419)
Proceeds from sale of short-term investments	84,692		75,025
Refund of deposits on aircraft	3,926
Payments of deposits on aircraft	(6,499)		(419)
Net cash used in investing activities	(94,184)		(20,738)
Financing activities:
Proceeds from issuance of Senior Notes due 2019	500,000
Premium and costs to retire debt early	(26,132)
Repayment of Senior Notes due 2018	(292,571)
Debt Issuance costs	(5,657)
Proceeds from line of credit	95,500		2,400
Payments on line of credit	(174,500)		(10,000)
Repurchase of common stock for payroll tax withholding requirements	(176)		(1,037)
Net cash provided by financing activities	96,464		(8,637)
Increase (decrease) in cash	8,402		728
Cash, beginning of period	934		2,849
Cash, end of period	9,336		3,577
Parent Company Only (issuer) [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities	5,047		31,082
Investing activities:
Purchase of property and equipment	(38,746)		(24,936)
Proceeds from asset dispositions	2,994		200
Purchase of short-term investments	(140,551)
Payments of deposits on aircraft			(419)
Proceeds from sale of short-term investments	84,692		4,417
Refund of deposits on aircraft	3,926
Payments of deposits on aircraft	(6,499)
Net cash used in investing activities	(94,184)		(20,738)
Financing activities:
Proceeds from issuance of Senior Notes due 2019	500,000
Premium and costs to retire debt early	(26,132)
Repayment of Senior Notes due 2018	(292,571)
Debt Issuance costs	(5,657)
Proceeds from line of credit	95,500		2,400
Payments on line of credit	(174,500)		(10,000)
Repurchase of common stock for payroll tax withholding requirements	(176)		(1,037)
Net cash provided by financing activities	96,464		(8,637)
Increase (decrease) in cash	7,327		1,707
Cash, beginning of period	52		552
Cash, end of period	7,379		2,259
Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities	1,075	[1]	(979)	[1]
Investing activities:
Purchase of property and equipment		[1]		[1]
Proceeds from asset dispositions		[1]		[1]
Purchase of short-term investments		[1]
Payments of deposits on aircraft				[1]
Proceeds from sale of short-term investments		[1]		[1]
Refund of deposits on aircraft		[1]
Payments of deposits on aircraft		[1]
Net cash used in investing activities		[1]		[1]
Financing activities:
Proceeds from issuance of Senior Notes due 2019		[1]
Premium and costs to retire debt early		[1]
Repayment of Senior Notes due 2018		[1]
Debt Issuance costs		[1]
Proceeds from line of credit		[1]		[1]
Payments on line of credit		[1]		[1]
Repurchase of common stock for payroll tax withholding requirements		[1]		[1]
Net cash provided by financing activities		[1]		[1]
Increase (decrease) in cash	1,075	[1]	(979)	[1]
Cash, beginning of period	882	[1]	2,297	[1]
Cash, end of period	1,957	[1]	1,318	[1]
Eliminations [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities
Investing activities:
Purchase of property and equipment
Proceeds from asset dispositions
Purchase of short-term investments
Payments of deposits on aircraft
Proceeds from sale of short-term investments
Refund of deposits on aircraft
Payments of deposits on aircraft
Net cash used in investing activities
Financing activities:
Proceeds from issuance of Senior Notes due 2019
Premium and costs to retire debt early
Repayment of Senior Notes due 2018
Debt Issuance costs
Proceeds from line of credit
Payments on line of credit
Repurchase of common stock for payroll tax withholding requirements
Net cash provided by financing activities
Increase (decrease) in cash
Cash, beginning of period
Cash, end of period

[1] Foreign subsidiaries represent minor subsidiaries and are included in the guarantors' subsidiaries amounts.