Condensed Consolidating Financial Information (Details 3) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Condensed Consolidating Statements of Cash Flows
Net Cash Provided By (Used In) Operating Activities	$ 252,163	$ 207,475
Cash Flows From Investing Activities:
Additions to property and equipment, including pre-delivery deposits	(361,290)	(232,717)
Net proceeds from disposition of property and equipment	978	0
Purchases of investments	(346,010)	0
Sales of investments	92,103	0
Net cash used in investing activities	(614,219)	(232,717)
Cash Flows From Financing Activities:
Proceeds from exercise of stock options	5,487	2,376
Long-term borrowings	293,430	132,000
Repayments of long-term debt and capital lease obligations	(46,392)	(45,200)
Debt issuance costs	(32)	(12,416)
Change in restricted cash	14,434	(16,000)
Net cash provided by financing activities	266,927	60,760
Net increase (decrease) in cash and cash equivalents	(95,129)	35,518
Cash and cash equivalents - Beginning of Period	423,384	405,880
Cash and cash equivalents - End of Period	328,255	441,398
Parent Issuer / Guarantor
Condensed Consolidating Statements of Cash Flows
Net Cash Provided By (Used In) Operating Activities	(6,859)	(7,244)
Cash Flows From Investing Activities:
Net payments to subsidiaries	(34,443)
Net payments from subsidiaries		5,553
Net cash used in investing activities	(34,443)	5,553
Cash Flows From Financing Activities:
Proceeds from exercise of stock options	5,487	2,376
Net cash provided by financing activities	5,487	2,376
Net increase (decrease) in cash and cash equivalents	(35,815)	685
Cash and cash equivalents - Beginning of Period	84,797	83,626
Cash and cash equivalents - End of Period	48,982	84,311
Subsidiary Issuer / Guarantor
Condensed Consolidating Statements of Cash Flows
Net Cash Provided By (Used In) Operating Activities	257,694	215,589
Cash Flows From Investing Activities:
Additions to property and equipment, including pre-delivery deposits	(358,538)	(220,272)
Net proceeds from disposition of property and equipment	978
Purchases of investments	(346,010)
Sales of investments	92,103
Net cash used in investing activities	(611,467)	(220,272)
Cash Flows From Financing Activities:
Long-term borrowings	293,430	132,000
Repayments of long-term debt and capital lease obligations	(46,392)	(45,200)
Debt issuance costs	(32)	(12,416)
Net payments from parent company	34,443	(5,553)
Change in restricted cash	14,434	(16,000)
Net cash provided by financing activities	295,883	52,831
Net increase (decrease) in cash and cash equivalents	(57,890)	48,148
Cash and cash equivalents - Beginning of Period	333,663	303,967
Cash and cash equivalents - End of Period	275,773	352,115
Non-Guarantor Subsidiaries
Condensed Consolidating Statements of Cash Flows
Net Cash Provided By (Used In) Operating Activities	1,328	(870)
Cash Flows From Investing Activities:
Additions to property and equipment, including pre-delivery deposits	(2,752)	(12,445)
Net cash used in investing activities	(2,752)	(12,445)
Cash Flows From Financing Activities:
Net increase (decrease) in cash and cash equivalents	(1,424)	(13,315)
Cash and cash equivalents - Beginning of Period	4,924	18,287
Cash and cash equivalents - End of Period	3,500	4,972
Eliminations
Cash Flows From Investing Activities:
Net payments to subsidiaries	34,443
Net payments from subsidiaries		(5,553)
Net cash used in investing activities	34,443	(5,553)
Cash Flows From Financing Activities:
Net payments from parent company	(34,443)	5,553
Net cash provided by financing activities	$ (34,443)	$ 5,553