Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Cash Flows [Abstract]
Net income	$ 156,575	$ 247,919	$ 147,874
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	356,021	310,850	298,664
Amortization of deferred financing costs	14,578	14,627	19,435
Amortization of lease premiums, discounts and incentives	22,636	15,269	11,714
Deferred income taxes	20,223	(496)	(8,948)
Non-cash share-based payment expense	15,830	11,488	13,148
Cash flow hedges reclassified into earnings	184	1,166	2,202
Sales-type and Direct Financing Leases, Profit (Loss)	25,842	0	0
Security deposits and maintenance payments included in earnings	(49,029)	(80,628)	(17,947)
Gain on the sale of flight equipment	(45,532)	(36,766)	(55,167)
Loss on extinguishment of debt	7,577	0	0
Impairment of aircraft	7,404	0	80,430
Other	206	3,032	1,476
Changes on certain assets and liabilities:
Accounts receivable	(13,162)	(12,328)	(6,734)
Other assets	2,594	5,065	(7,655)
Accounts payable, accrued expenses and other liabilities	(5,483)	10,526	13,857
Lease rentals received in advance	19,954	32,868	(1,478)
Net cash and restricted cash provided by operating activities	536,418	522,592	490,871
Cash flows from investing activities:
Acquisition and improvement of flight equipment	(1,172,370)	(1,317,497)	(1,038,343)
Proceeds from sale of flight equipment	361,747	338,831	833,576
Net investment in direct financing and sales-type leases	0	(15,783)	(331,721)
Proceeds from Collection of Finance Receivables	0	29,961	32,184
Aircraft purchase deposits and progress payments, net of returned deposits and aircraft sales deposits	(760)	15,494	7,681
Unconsolidated equity method investment and associated costs	(15,175)	(3,350)	0
Distributions from unconsolidated equity method investment in excess of earnings	36,750	3,900	0
Other	4,259	4,745	(5,122)
Net Cash Provided by (Used in) Investing Activities	(784,029)	(974,687)	(517,107)
Cash flows from financing activities:
Repurchase of shares	(36,739)	(71,421)	(4,862)
Proceeds from secured and unsecured debt financings	2,116,848	1,413,901	675,000
Repayments of secured and unsecured debt financings	(1,817,558)	(969,139)	(878,534)
Deferred financing costs	(13,800)	(11,642)	(8,540)
Debt extinguishment costs	(7,183)	0	0
Security deposits and maintenance payments received	202,833	203,925	192,830
Security deposits and maintenance payments returned	(117,872)	(90,803)	(141,185)
Dividends paid	(91,328)	(88,730)	(83,433)
Net cash and restricted cash provided by (used in) financing activities	235,201	386,091	(248,724)
Net decrease in cash and restricted cash	(12,410)	(66,004)	(274,960)
Cash and restricted cash at beginning of year	167,853	233,857	508,817
Cash and restricted cash at end of year	155,443	167,853	233,857
Reconciliation to Consolidated Balance Sheets:
Unrestricted and restricted cash and cash equivalents	155,443	167,853	508,817
Supplemental disclosures of cash flow information:
Cash paid during the year for interest	246,026	214,350	228,125
Cash (received) paid during the year for income taxes	(656)	6,254	4,576
Supplemental disclosures of non-cash investing activities:
Advance lease rentals, security deposits, maintenance payments, other liabilities and other assets settled in sale of flight equipment	90,397	71,837	132,585
Advance lease rentals, security deposits, maintenance payments, other liabilities and other assets assumed in asset acquisitions	31,958	63,432	149,100
Transfers from Flight equipment held for lease to Net investment in direct financing and sales-type leases and Other assets	$ 104,838	$ 11,202	$ 154,213