Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Statement of Cash Flows [Abstract]
Net income (loss)	$ 35,323	$ 56,292
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	157,428	151,717
Amortization of Debt Issuance Costs and Discounts	9,125	9,470
Amortization of lease premiums, discounts and incentives	6,392	4,898
Deferred income taxes	(833)	2,243
Non-cash share-based payment expense	8,130	3,737
Cash flow hedges reclassified into earnings	1,156	8,369
Security deposits and maintenance payments included in earnings	(23,063)	(5,651)
Gain on sale of flight equipment	(14,284)	(15,005)
Asset Impairment Charges	80,430	16,723
Other	1,211	(2,843)
Changes in certain assets and liabilities:
Accounts receivable	2,090	3,262
Other assets	(11,407)	(85)
Accounts payable, accrued expenses and other liabilities	(2,194)	4,284
Lease rentals received in advance	(2,115)	(2,714)
Net Cash Provided by (Used in) Operating Activities	247,389	234,697
Cash flows from investing activities:
Acquisition and improvement of flight equipment	(148,364)	(478,026)
Proceeds from sale of flight equipment	238,277	339,507
Payments for Other Deposits	(2,892)	(9,801)
Payments to Acquire Finance Receivables	(119,971)	(78,365)
Collections on finance and sales-type leases	17,185	7,833
Payments to Acquire Interest in Subsidiaries and Affiliates	0	(11,688)
Other	88	(509)
Net Cash and Restricted Cash Provided By (Used In) Investing Activities	(15,677)	(231,049)
Cash flows from financing activities:
Repurchase of shares	(2,513)	(33,854)
Proceeds from secured and unsecured debt financings	500,000	787,310
Repayments of secured and unsecured debt financings	(667,472)	(459,021)
Deferred financing costs	(8,540)	(16,121)
Restricted Secured Liquidity Facility Collateral, Financing Activities	0	65,000
Secured Liquidity Facility Collateral, Financing Activities	0	(65,000)
Security deposits and maintenance payments received	87,185	72,572
Security deposits and maintenance payments returned	(77,593)	(26,094)
Dividends paid	(40,948)	(37,830)
Net Cash and Restricted Cash Provided by (Used In) Financing Activities	(209,881)	286,962
Cash and Restricted Cash, Period Increase (Decrease)	21,831	290,610
Cash and Restricted Cash at Beginning of Period	508,817	254,041
Cash and Restricted Cash at End of Period	530,648	544,651
Supplemental disclosures of cash flow information:
Cash paid for interest, net of capitalized interest	117,420	104,534
Cash paid for income taxes	2,200	2,809
Supplemental disclosures of non-cash investing activities:
Advance lease rentals, security deposits and maintenance payments assumed in asset acquisitions	3,653	105,801
Security Deposits Maintenance Liabilities And Other Liabilities Settled In Sale Of Flight Equipment	44,603	21,159
Property, Plant and Equipment, Transfers and Changes	$ 99,162	$ 86,267