Financial Derivative Instruments (Details 2)	3 Months Ended	9 Months Ended																																					12 Months Ended	9 Months Ended
	Sep. 30, 2014 Negative arbitrage derivative USD ($)	Sep. 30, 2014 Negative arbitrage derivative USD ($)	Sep. 30, 2014 Derivatives designated as hedging instruments Interest rate derivative USD ($)	Dec. 31, 2013 Derivatives designated as hedging instruments Interest rate derivative USD ($)	Sep. 30, 2014 Derivatives designated as hedging instruments Interest rate derivative Prepaid expenses and other USD ($)	Dec. 31, 2013 Derivatives designated as hedging instruments Interest rate derivative Prepaid expenses and other USD ($)	Sep. 30, 2014 Derivatives designated as hedging instruments Interest rate derivative Long-term prepayments and other USD ($)		Dec. 31, 2013 Derivatives designated as hedging instruments Interest rate derivative Long-term prepayments and other USD ($)		Sep. 30, 2014 Derivatives designated as hedging instruments Foreign currency derivatives Prepaid expenses and other USD ($)	Dec. 31, 2013 Derivatives designated as hedging instruments Foreign currency derivatives Prepaid expenses and other USD ($)	Sep. 30, 2014 Derivatives designated as hedging instruments Foreign currency derivatives Long-term prepayments and other USD ($)	Dec. 31, 2013 Derivatives designated as hedging instruments Foreign currency derivatives Long-term prepayments and other USD ($)	Sep. 30, 2014 Derivatives designated as hedging instruments Foreign currency derivatives Japanese yen Prepaid expenses and other JPY (¥)	Dec. 31, 2013 Derivatives designated as hedging instruments Foreign currency derivatives Japanese yen Prepaid expenses and other JPY (¥)	Sep. 30, 2014 Derivatives designated as hedging instruments Foreign currency derivatives Japanese yen Long-term prepayments and other JPY (¥)	Dec. 31, 2013 Derivatives designated as hedging instruments Foreign currency derivatives Japanese yen Long-term prepayments and other JPY (¥)	Dec. 31, 2013 Derivatives designated as hedging instruments Foreign currency derivatives Korean Won Prepaid expenses and other KRW	Sep. 30, 2014 Derivatives designated as hedging instruments Foreign currency derivatives Australian dollar Prepaid expenses and other AUD	Dec. 31, 2013 Derivatives designated as hedging instruments Foreign currency derivatives Australian dollar Prepaid expenses and other AUD	Sep. 30, 2014 Derivatives designated as hedging instruments Foreign currency derivatives Australian dollar Long-term prepayments and other AUD	Dec. 31, 2013 Derivatives designated as hedging instruments Foreign currency derivatives Australian dollar Long-term prepayments and other AUD	Dec. 31, 2013 Derivatives designated as hedging instruments Foreign currency derivatives New Zealand Dollars Prepaid expenses and other NZD	Sep. 30, 2014 Derivatives not designated as hedging instruments Negative arbitrage derivative Other accrued liabilities USD ($)	Dec. 31, 2013 Derivatives not designated as hedging instruments Negative arbitrage derivative Other accrued liabilities USD ($)	Dec. 31, 2013 Derivatives not designated as hedging instruments Negative arbitrage derivative Other Noncurrent Liabilities USD ($)		Sep. 30, 2014 Derivatives not designated as hedging instruments Foreign currency derivatives Prepaid expenses and other USD ($)	Dec. 31, 2013 Derivatives not designated as hedging instruments Foreign currency derivatives Prepaid expenses and other USD ($)	Sep. 30, 2014 Derivatives not designated as hedging instruments Foreign currency derivatives Long-term prepayments and other USD ($)	Dec. 31, 2013 Derivatives not designated as hedging instruments Foreign currency derivatives Other accrued liabilities USD ($)	Sep. 30, 2014 Derivatives not designated as hedging instruments Foreign currency derivatives Japanese yen Prepaid expenses and other JPY (¥)	Dec. 31, 2013 Derivatives not designated as hedging instruments Foreign currency derivatives Japanese yen Prepaid expenses and other JPY (¥)	Sep. 30, 2014 Derivatives not designated as hedging instruments Foreign currency derivatives Japanese yen Long-term prepayments and other JPY (¥)	Sep. 30, 2014 Derivatives not designated as hedging instruments Foreign currency derivatives Australian dollar Prepaid expenses and other AUD	Dec. 31, 2013 Derivatives not designated as hedging instruments Foreign currency derivatives Australian dollar Prepaid expenses and other AUD	Sep. 30, 2014 Derivatives not designated as hedging instruments Foreign currency derivatives Australian dollar Long-term prepayments and other AUD	Dec. 31, 2013 Derivatives not designated as hedging instruments Fuel derivative contracts Prepaid expenses and other USD ($) gal	Sep. 30, 2014 Derivatives not designated as hedging instruments Fuel derivative contracts Other accrued liabilities USD ($) gal	Dec. 31, 2013 Enhanced Equipment Trust Certificates (EETC) USD ($) pass_through_trust
Fair Value of Derivatives
Number of pass-through trusts																																									2
Aggregate principal amount issued																																									$ 444,500,000
Amount reduced in connection with the first interest payment made to the trust	3,200,000	12,400,000
Notional Amount			59,000,000	63,800,000											7,218,469,000	10,500,321,000	3,384,130,000	1,980,949,000	10,895,370,000	52,209,000	62,659,000	9,707,000	16,681,000	4,821,000	444,540,000	444,540,000							9,415,313,000	6,180,000	3,910,000,000	48,981,000	58,000	9,700,000
Notional Amount (Volume)																																							84,714,000	93,211,000
Gross fair value of assets, current					73,000	196,000					7,448,000	9,946,000																	1,529,000	577,000		298,000							13,587,000	899,000
Gross fair value of assets, noncurrent							379,000	[1]	925,000	[2]			2,514,000	1,673,000																	360,000
Gross fair value of liabilities, current											(14,000)	(450,000)													(500,000)	(12,250,000)			(104,000)	(229,000)		(509,000)							(7,494,000)	(19,569,000)
Gross fair value of liabilities, noncurrent													0														(615,000)	[3]
Net derivative position					$ 73,000	$ 196,000	$ 379,000	[1]	$ 925,000	[2]	$ 7,434,000	$ 9,496,000	$ 2,514,000	$ 1,673,000											$ (500,000)	$ (12,250,000)	$ (615,000)	[3]	$ 1,425,000	$ 348,000	$ 360,000	$ (211,000)							$ 6,093,000	$ (18,670,000)

[1] Represents the noncurrent portion of the $59.0 million interest rate derivative with final maturity in April 2023.

[2] Represents the noncurrent portion of the $64 million interest rate derivative with final maturity in April 2023.

[3] Represents the noncurrent portion of the $445 million negative arbitrage derivative with final maturity in January 2015.