Other Assets (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Principal components of other assets
Debt investments	$ 0	$ 40,388
Deferred debt issuance costs, net of amortization of $54,146 and $58,802, respectively	47,103	55,087
Deferred federal income tax asset	26,414	22,207
Lease incentives and lease premiums, net of amortization of $26,902 and $36,787, respectively	84,860	62,822
Flight equipment held for sale	300	0
Other assets	18,565	6,260
Total other assets	177,242	186,764
Amortization of deferred debt issuance costs	58,802	54,146
Amortization of lease incentives and lease premiums	$ 36,787	$ 26,902