CONDENSED CONSOLIDATING FINANCIAL INFORMATION - Condensed Consolidating Statements of Cash Flows (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	$ 57,706	$ 24,882
Investing activities:
Purchase of property and equipment	(50,004)	(32,407)
Proceeds from asset dispositions	37,255	8,587
Deposits returned on aircraft, net	3,150
Deposits paid on aircraft	(571)	(9,126)
Purchase of short-term investments	(246,375)	(102,436)
Net cash used in investing activities	(36,296)	(40,540)
Financing activities:
Proceeds from line of credit	41,965	66,081
Payments on line of credit	(52,997)	(54,090)
Repurchase of common stock	(1,037)
Net cash (used in) provided by financing activities	(12,069)	11,991
Increase (decrease) in cash	9,341	(3,667)
Cash, beginning of period	2,849	5,091
Cash, end of period	12,190	1,424
Parent Company Only (issuer) [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	48,970	24,288
Investing activities:
Purchase of property and equipment	(50,004)	(32,407)
Proceeds from asset dispositions	37,255	8,587
Deposits returned on aircraft, net	2,579
Deposits paid on aircraft		(9,126)
Purchase of short-term investments	(246,375)	(7,594)
Proceeds from sale of short-term investments	220,249
Net cash used in investing activities	(36,296)	(40,540)
Financing activities:
Proceeds from line of credit	41,965	66,081
Payments on line of credit	(52,997)	(54,090)
Repurchase of common stock	(1,037)
Net cash (used in) provided by financing activities	(12,069)	11,991
Increase (decrease) in cash	605	(4,261)
Cash, beginning of period	552	4,313
Cash, end of period	1,157	52
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	8,736	594
Investing activities:
Purchase of property and equipment
Proceeds from asset dispositions
Deposits returned on aircraft, net
Deposits paid on aircraft
Purchase of short-term investments
Proceeds from sale of short-term investments
Net cash used in investing activities
Financing activities:
Proceeds from line of credit
Payments on line of credit
Repurchase of common stock
Net cash (used in) provided by financing activities
Increase (decrease) in cash	8,736	594
Cash, beginning of period	2,297	778
Cash, end of period	11,033	1,372
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities
Investing activities:
Purchase of property and equipment
Proceeds from asset dispositions
Deposits returned on aircraft, net
Deposits paid on aircraft
Purchase of short-term investments
Proceeds from sale of short-term investments
Net cash used in investing activities
Financing activities:
Proceeds from line of credit
Payments on line of credit
Repurchase of common stock
Net cash (used in) provided by financing activities
Increase (decrease) in cash
Cash, beginning of period
Cash, end of period
Consolidated [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	57,706	24,882
Investing activities:
Purchase of property and equipment	(50,004)	(32,407)
Proceeds from asset dispositions	37,255	8,587
Deposits returned on aircraft, net	2,579
Deposits paid on aircraft		(9,126)
Purchase of short-term investments	(246,375)	(7,594)
Proceeds from sale of short-term investments	220,249
Net cash used in investing activities	(36,296)	(40,540)
Financing activities:
Proceeds from line of credit	41,965	66,081
Payments on line of credit	(52,997)	(54,090)
Repurchase of common stock	(1,037)
Net cash (used in) provided by financing activities	(12,069)	11,991
Increase (decrease) in cash	9,341	(3,667)
Cash, beginning of period	2,849	5,091
Cash, end of period	$ 12,190	$ 1,424