SCHEDULE I - Parent Company Information - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income	$ 62,158	$ 14,069	$ 6,460
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation expense	66,023	66,280	69,424
Write-down of equipment	24,930	9,514	9,181
Stock-based compensation expenses	4,270	3,717	4,150
Excess tax benefit from stock-based compensation		236	26
Amortization of deferred costs	5,183	4,271	4,307
Allowances and provisions	162	(571)	697
Gain on sale of leased equipment	(4,929)	(3,482)	(8,320)
Gain on insurance settlement	(1,288)
Income from joint ventures	(7,158)	(1,813)	(1,175)
Loss on extinguishment of debt		137	(1,151)
Deferred income taxes	(26,393)	9,100	6,027
Changes in assets and liabilities:
Receivables	(2,525)	(2,287)	(5,769)
Spare parts inventory	(1,855)	(5,093)	3,828
Intangibles		(1,511)
Other assets	(970)	(1,707)	(2,635)
Accounts payable and accrued expenses	1,129	2,329	1,677
Maintenance reserves	7,994	548	4,580
Security deposits	6,246	(4,048)	5,747
Unearned lease revenue	2,279	732	748
Net cash provided by operating activities	135,256	90,421	97,802
Cash flows from investing activities:
Proceeds from sale of equipment held for operating lease (net of selling expenses)	43,791	62,525	41,608
Capital contribution to joint ventures		(5,545)	(630)
Proceeds from Insurance Settlement, Investing Activities	14,886
Distributions received from joint venture	1,880	1,167	1,304
Maintenance rights payments received			5,802
Purchase of equipment held for operating lease	(373,483)	(173,662)	(174,772)
Purchase of maintenance rights		(5,530)	(8,844)
Purchase of property, equipment and furnishings	(10,788)	(1,006)	(3,988)
Net cash used in investing activities	(323,714)	(122,051)	(139,520)
Cash flows from financing activities:
Proceeds from issuance of notes payable	686,200	149,000	192,700
Debt issuance cost	(8,262)	(3,808)	(13)
Proceeds from shares issued under stock compensation plans	177	155	518
Preferred stock dividends	(1,311)
Cancellation of restricted stock units in satisfaction of withholding tax	(1,094)	(1,369)	(1,558)
Security deposit	(2,261)	455	(1,606)
Repurchase of common stock	(3,546)	(28,958)	(16,500)
Proceeds from issuance of preferred stock	29,665	19,752
Principal payments on notes payable	(496,160)	(113,981)	(153,816)
Net cash used in financing activities	203,408	21,246	19,725
Increase/(decrease) in cash, cash equivalents and restricted cash	14,950	(10,384)	(21,993)
Cash and cash equivalents at beginning of period	10,076
Cash and cash equivalents at end of period	7,052	10,076
Net cash paid for:
Interest	42,817	37,319	35,568
Income Taxes	440	459	353
Supplemental disclosures of non-cash investing activities:
Engines and equipment transferred from Held for operating Lease to Held for sale	45,018	28,560	22,079
Engines and equipment transferred from Held for sale to Spare parts inventory	210		6,061
Aircraft transferred from Property, equipment and furnishings to Assets held for lease		2,925
Accrued Preferred Stock Dividends	783	281
Accretion of preferred stock issuance costs	46	8
Parent Company
Cash flows from operating activities:
Net income	62,158	14,069	6,460
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in income of subsidiaries	(54,043)	(10,782)	(6,632)
Depreciation expense	40,560	43,451	40,623
Write-down of equipment	17,881	5,989	6,764
Stock-based compensation expenses	4,270	3,717	4,150
Excess tax benefit from stock-based compensation		236	26
Amortization of deferred costs	3,085	2,704	2,646
Allowances and provisions	76	(1)	(17)
Gain on sale of leased equipment	(3,696)	(3,322)	(2,420)
Gain on insurance settlement	(1,288)
Income from joint ventures	(7,158)	(1,813)	(1,175)
Loss on extinguishment of debt		137
Deferred income taxes	4,843	4,710	1,806
Changes in assets and liabilities:
Receivables	5,366	(4,884)	(865)
Spare parts inventory	5,612	(1,608)	4,547
Intangibles		(750)
Other assets	(4,259)	(2,648)	(2,420)
Accounts payable and accrued expenses	2,370	3,723	4,471
Due to / from subsidiaries	8,584	(4,437)	(1,242)
Maintenance reserves	7,906	16,583	5,227
Security deposits	6,876	(2,283)	5,354
Unearned lease revenue	906	878	817
Net cash provided by operating activities	100,049	63,669	68,120
Cash flows from investing activities:
Increase in investment in subsidiaries	(45,609)	(2,329)	(23,923)
Distributions received from subsidiaries	347,626	15,500	3,791
Proceeds from sale of equipment held for operating lease (net of selling expenses)	33,118	60,893	18,792
Capital contribution to joint ventures		(5,545)	(630)
Proceeds from Insurance Settlement, Investing Activities	14,886
Distributions received from joint venture	1,880	1,167	1,304
Maintenance rights payments received			5,802
Purchase of equipment held for operating lease	(354,918)	(167,874)	(161,888)
Purchase of maintenance rights		(5,530)	(8,844)
Purchase of property, equipment and furnishings	(268)	(443)	(3,736)
Net cash used in investing activities	(3,285)	(104,161)	(169,332)
Cash flows from financing activities:
Proceeds from issuance of notes payable	350,500	149,000	192,700
Debt issuance cost		(3,808)	(13)
Proceeds from shares issued under stock compensation plans	177	155	518
Preferred stock dividends	(1,311)
Cancellation of restricted stock units in satisfaction of withholding tax	(1,094)	(1,369)	(1,558)
Security deposit	(2,261)	455	(1,606)
Repurchase of common stock	(3,546)	(28,958)	(16,500)
Proceeds from issuance of preferred stock	29,663	19,752
Principal payments on notes payable	(470,606)	(93,055)	(71,846)
Net cash used in financing activities	(98,478)	42,172	101,695
Increase/(decrease) in cash, cash equivalents and restricted cash	(1,714)	1,680	483
Cash and cash equivalents at beginning of period	4,574	2,894	2,411
Cash and cash equivalents at end of period	2,860	4,574	2,894
Net cash paid for:
Interest	21,761	20,619	16,462
Income Taxes	180	20	75
Supplemental disclosures of non-cash investing activities:
Engines and equipment transferred to the parent from its subsidiaries	17,910	229	41,410
Engines and equipment transferred from Held for operating Lease to Held for sale	31,571	18,194	21,786
Engines and equipment transferred from Held for sale to Spare parts inventory			$ 6,061
Aircraft transferred from Property, equipment and furnishings to Assets held for lease		2,925
Transferred from property, equipment and furnishings to Equipment held for Lease	783	281
Accrued Preferred Stock Dividends	46	8
Accretion of preferred stock issuance costs	$ 46	$ 8