SCHEDULE I - Parent Company Information - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net income attributable to common shareholders	$ 14,069	$ 6,460	$ 7,180
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation expense	66,280	69,424	65,314
Write-down of equipment	9,514	9,181	5,602
Stock-based compensation expenses	3,717	4,150	3,509
Amortization of deferred costs	4,271	4,307	4,319
Amortization of interest rate derivative cost			(499)
Allowances and provisions	(571)	697	(81)
Gain on sale of leased equipment	(3,482)	(8,320)	(5,882)
Loss (gain) on debt extinguishment	137	(1,151)
Income from joint ventures	(1,813)	(1,175)	(1,329)
Deferred income taxes	9,100	6,027	4,110
Changes in assets and liabilities:
Receivables	(2,287)	(5,769)	4,812
Spare parts inventory	(5,093)	3,828	(5,964)
Intangibles	(1,511)
Other assets	(1,707)	(2,635)	(590)
Accounts payable and accrued expenses	2,329	1,677	(1,998)
Maintenance reserves	548	4,580	(10,861)
Security deposits	(4,048)	5,747	1,158
Unearned lease revenue	732	748	793
Net cash provided by operating activities	100,913	107,412	62,762
Cash flows from investing activities:
Proceeds from sale of equipment held for operating lease (net of selling expenses)	62,525	41,608	43,632
Capital contribution to joint ventures	(5,545)	(630)	(17,623)
Distributions received from joint venture	1,167	1,304	847
Maintenance rights payments received		5,802
Purchase of equipment held for operating lease	(173,662)	(174,772)	(119,008)
Purchase of maintenance rights	(5,530)	(8,844)	(9,098)
Purchase of property, equipment and furnishings	(1,006)	(3,988)	(13,831)
Net cash used in investing activities	(123,396)	(156,283)	(108,715)
Cash flows from financing activities:
Proceeds from issuance of notes payable	149,000	192,700	154,395
Debt issuance cost	(3,808)	(13)	(5,074)
Proceeds from shares issued under stock compensation plans	155	518	410
Cancellation of restricted stock units in satisfaction of withholding tax	(1,369)	(1,558)	(1,544)
Security deposit	455	(1,606)	4,553
Repurchase of common stock	(28,958)	(16,500)	(5,352)
Excess tax benefit from stock-based compensation	236	26	311
Proceeds from Issuance of Redeemable Convertible Preferred Stock	19,752
Principal payments on notes payable	(113,981)	(153,816)	(101,054)
Net cash provided by (used in) financing activities	22,827	45,110	46,645
Increase/(Decrease) in cash and cash equivalents	344	(3,761)	692
Cash and cash equivalents at beginning of period	9,732	13,493	12,801
Cash and cash equivalents at end of period	10,076	9,732	13,493
Net cash paid for:
Interest	37,319	35,568	33,132
Income Taxes	459	353	210
Supplemental disclosures of non-cash investing activities:
Engines and equipment, transferred from Held for Operating Lease to Held for Sale but not settled	28,560	22,079	3,071
Engines and equipment, transferred to (from) the parent to its subsidiaries	229	41,410	120,880
Equipment Held For Sale Transfer To Spare Parts Inventory	0	6,061	9,649
Transferred from property, equipment and furnishings to Assets held for Lease	2,925
Temporary Equity, Dividends, Adjustment	281
Temporary Equity, Accretion to Redemption Value, Adjustment	8
Dividends, Preferred Stock	281
Parent Company
Cash flows from operating activities:
Net income attributable to common shareholders	14,069	6,460	7,180
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in income of subsidiaries	(10,782)	(6,632)	(7,130)
Depreciation expense	43,451	40,623	29,276
Write-down of equipment	5,989	6,764	4,681
Stock-based compensation expenses	3,717	4,150	3,509
Amortization of deferred costs	2,704	2,646	2,391
Amortization of interest rate derivative cost			(499)
Allowances and provisions	(1)	(17)	34
Gain on sale of leased equipment	(3,322)	(2,420)	(2,276)
Loss (gain) on debt extinguishment	137
Income from joint ventures	(1,813)	(1,175)	(1,329)
Deferred income taxes	4,710	1,806	1,478
Changes in assets and liabilities:
Receivables	(4,884)	(865)	(1,204)
Spare parts inventory	(1,608)	4,547	(5,533)
Intangibles	(750)
Other assets	(2,648)	(2,420)	(942)
Accounts payable and accrued expenses	3,723	4,471	2,425
Due to / from subsidiaries	(4,437)	(1,242)	(17,651)
Maintenance reserves	16,583	5,227	17,563
Security deposits	(2,283)	5,354	2,303
Unearned lease revenue	878	817	1,048
Net cash provided by operating activities	63,433	68,094	35,324
Cash flows from investing activities:
Increase in investment in subsidiaries	(2,329)	(23,923)	(9,666)
Distributions received from subsidiaries	15,500	3,791	17,582
Proceeds from sale of equipment held for operating lease (net of selling expenses)	60,893	18,792	21,360
Capital contribution to joint ventures	(5,545)	(630)	(17,623)
Distributions received from joint venture	1,167	1,304	847
Maintenance rights payments received		5,802
Purchase of equipment held for operating lease	(167,874)	(161,888)	(101,710)
Purchase of maintenance rights	(5,530)	(8,844)	(3,296)
Purchase of property, equipment and furnishings	(443)	(3,736)	(13,767)
Net cash used in investing activities	(104,161)	(169,332)	(106,273)
Cash flows from financing activities:
Proceeds from issuance of notes payable	149,000	192,700	154,395
Debt issuance cost	(3,808)	(13)	(5,074)
Proceeds from shares issued under stock compensation plans	155	518	410
Cancellation of restricted stock units in satisfaction of withholding tax	(1,369)	(1,558)	(1,544)
Security deposit	455	(1,606)	4,553
Repurchase of common stock	(28,958)	(16,500)	(5,352)
Excess tax benefit from stock-based compensation	236	26	311
Proceeds from Issuance of Redeemable Convertible Preferred Stock	19,752
Principal payments on notes payable	(93,055)	(71,846)	(75,859)
Net cash provided by (used in) financing activities	42,408	101,721	71,840
Increase/(Decrease) in cash and cash equivalents	1,680	483	891
Cash and cash equivalents at beginning of period	2,894	2,411	1,520
Cash and cash equivalents at end of period	4,574	2,894	2,411
Net cash paid for:
Interest	20,619	16,462	11,110
Income Taxes	20	75	76
Supplemental disclosures of non-cash investing activities:
Engines and equipment, transferred from Held for Operating Lease to Held for Sale but not settled	18,194	21,786	3,071
Equipment Held For Sale Transfer To Spare Parts Inventory		$ 6,061	$ 9,649
Temporary Equity, Dividends, Adjustment	281
Temporary Equity, Accretion to Redemption Value, Adjustment	$ 8