Condensed Consolidating Financial Information (Details 3) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Condensed Consolidating Statements of Cash Flows
Net cash provided by (Used In) Operating Activities	$ 207,475	$ 249,394
Cash flows from Investing Activities:
Additions to property and equipment, including pre-delivery deposits	(232,717)	(215,950)
Net cash used in investing activities	(232,717)	(215,950)
Cash flows from Financing Activities:
Proceeds from exercise of stock options	2,376	1,263
Long-term borrowings	132,000	133,000
Repayments of long-term debt and capital lease obligations	(45,200)	(35,219)
Debt issuance costs	(12,416)	(3,118)
Change in restricted cash	(16,000)
Net cash provided by financing activities	60,760	95,926
Net increase in cash and cash equivalents	35,518	129,370
Cash and cash equivalents - Beginning of Period	405,880	304,115
Cash and cash equivalents - End of Period	441,398	433,485
Parent Issuer / Guarantor
Condensed Consolidating Statements of Cash Flows
Net cash provided by (Used In) Operating Activities	(7,244)	(7,824)
Cash flows from Investing Activities:
Net payments from subsidiaries	5,553	9,735
Net cash used in investing activities	5,553	9,735
Cash flows from Financing Activities:
Proceeds from exercise of stock options	2,376	1,263
Net cash provided by financing activities	2,376	1,263
Net increase in cash and cash equivalents	685	3,174
Cash and cash equivalents - Beginning of Period	83,626	97,219
Cash and cash equivalents - End of Period	84,311	100,393
Subsidiary Issuer / Guarantor
Condensed Consolidating Statements of Cash Flows
Net cash provided by (Used In) Operating Activities	215,589	257,509
Cash flows from Investing Activities:
Additions to property and equipment, including pre-delivery deposits	(220,272)	(215,950)
Net cash used in investing activities	(220,272)	(215,950)
Cash flows from Financing Activities:
Long-term borrowings	132,000	133,000
Repayments of long-term debt and capital lease obligations	(45,200)	(35,219)
Debt issuance costs	(12,416)	(3,118)
Net payments to parent company	(5,553)	(9,735)
Change in restricted cash	(16,000)
Net cash provided by financing activities	52,831	84,928
Net increase in cash and cash equivalents	48,148	126,487
Cash and cash equivalents - Beginning of Period	303,967	205,656
Cash and cash equivalents - End of Period	352,115	332,143
Non-Guarantor Subsidiaries
Condensed Consolidating Statements of Cash Flows
Net cash provided by (Used In) Operating Activities	(870)	(291)
Cash flows from Investing Activities:
Additions to property and equipment, including pre-delivery deposits	(12,445)
Net cash used in investing activities	(12,445)
Cash flows from Financing Activities:
Net increase in cash and cash equivalents	(13,315)	(291)
Cash and cash equivalents - Beginning of Period	18,287	1,240
Cash and cash equivalents - End of Period	4,972	949
Eliminations
Cash flows from Investing Activities:
Net payments from subsidiaries	(5,553)	(9,735)
Net cash used in investing activities	(5,553)	(9,735)
Cash flows from Financing Activities:
Net payments to parent company	5,553	9,735
Net cash provided by financing activities	$ 5,553	$ 9,735