Condensed Consolidating Financial Information (Details 2) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 441,398	$ 405,880	$ 433,485	$ 304,115
Restricted cash	19,434	5,000
Accounts receivable, net	79,258	80,750
Spare parts and supplies, net	20,857	27,552
Deferred tax assets, net	19,983	17,675
Prepaid expenses and other	35,347	35,001
Total	616,277	571,858
Property and equipment at cost	1,564,022	1,318,213
Less accumulated depreciation and amortization	(307,556)	(249,495)
Property and equipment, net	1,256,466	1,068,718
Long-term prepayments and other	88,323	55,629
Restricted cash	1,566
Deferred tax assets, net	5,357	36,376
Goodwill and other intangible assets, net	131,263	133,243
Total Assets	2,099,252	1,865,824
Current liabilities:
Accounts payable	88,145	82,084
Air traffic liability	452,599	388,646
Other accrued liabilities	90,431	74,828
Current maturities of long-term debt and capital lease obligations	110,960	108,232
Total	742,135	653,790
Long-term debt, less discount, and capital lease obligations	651,778	553,009
Other liabilities and deferred credits:
Accumulated pension and other postretirement benefit obligations	350,407	352,460
Other liabilities and deferred credits	40,438	37,963
Total	390,845	390,423
Shareholders' Equity	314,494	268,602
Total Liabilities and Shareholders' Equity	2,099,252	1,865,824
Parent Issuer / Guarantor
Current assets:
Cash and cash equivalents	84,311	83,626	100,393	97,219
Accounts receivable, net	2,032	2,032
Deferred tax assets, net	411	704
Prepaid expenses and other	3
Total	86,757	86,362
Long-term prepayments and other	1,302	1,695
Deferred tax assets, net	13,106	8,439
Intercompany receivable	26,506	33,110
Investment in consolidated subsidiaries	263,378	213,275
Total Assets	391,049	342,881
Current liabilities:
Accounts payable	802	292
Other accrued liabilities	220	1,310
Total	1,022	1,602
Long-term debt, less discount, and capital lease obligations	75,533	72,677
Other liabilities and deferred credits:
Shareholders' Equity	314,494	268,602
Total Liabilities and Shareholders' Equity	391,049	342,881
Reduction of investment in consolidated subsidiaries		29,015
Subsidiary Issuer / Guarantor
Current assets:
Cash and cash equivalents	352,115	303,967	332,143	205,656
Restricted cash	19,434	5,000
Accounts receivable, net	77,046	78,949
Spare parts and supplies, net	20,857	27,552
Deferred tax assets, net	19,572	16,971
Prepaid expenses and other	35,344	35,001
Total	524,368	467,440
Property and equipment at cost	1,533,121	1,299,757
Less accumulated depreciation and amortization	(307,556)	(249,495)
Property and equipment, net	1,225,565	1,050,262
Long-term prepayments and other	87,021	53,934
Restricted cash	1,566
Deferred tax assets, net		27,937
Goodwill and other intangible assets, net	131,263	133,243
Total Assets	1,969,783	1,732,816
Current liabilities:
Accounts payable	87,327	81,758
Air traffic liability	451,422	386,677
Other accrued liabilities	90,211	73,518
Current maturities of long-term debt and capital lease obligations	110,960	108,232
Total	739,920	650,185
Long-term debt, less discount, and capital lease obligations	576,245	480,332
Intercompany payable	26,506	33,110
Other liabilities and deferred credits:
Accumulated pension and other postretirement benefit obligations	350,407	352,460
Other liabilities and deferred credits	40,438	37,963
Deferred tax liabilities, net	7,749
Total	398,594	390,423
Shareholders' Equity	228,518	178,766
Total Liabilities and Shareholders' Equity	1,969,783	1,732,816
Non-Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	4,972	18,287	949	1,240
Accounts receivable, net	278	13
Total	5,250	18,300
Property and equipment at cost	30,901	18,456
Property and equipment, net	30,901	18,456
Total Assets	36,151	36,756
Current liabilities:
Accounts payable	114	278
Air traffic liability	1,177	1,969
Total	1,291	2,247
Other liabilities and deferred credits:
Shareholders' Equity	34,860	34,509
Total Liabilities and Shareholders' Equity	36,151	36,756
Eliminations
Current assets:
Accounts receivable, net	(98)	(244)
Total	(98)	(244)
Deferred tax assets, net	(7,749)
Intercompany receivable	(26,506)	(33,110)
Investment in consolidated subsidiaries	(263,378)	(213,275)
Total Assets	(297,731)	(246,629)
Current liabilities:
Accounts payable	(98)	(244)
Total	(98)	(244)
Intercompany payable	(26,506)	(33,110)
Other liabilities and deferred credits:
Deferred tax liabilities, net	(7,749)
Total	(7,749)
Shareholders' Equity	(263,378)	(213,275)
Total Liabilities and Shareholders' Equity	$ (297,731)	$ (246,629)