CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Operating Activities
Net income	$ 253,391	$ 255,998	$ 190,411
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of flight equipment	397,760	336,657	280,037
Stock-based compensation	17,022	16,048	21,614
Deferred taxes	138,608	137,107	102,636
Tax benefits from stock-based compensation arrangements		(7,011)	(2,115)
Amortization of discounts and debt issuance costs	30,507	27,772	23,627
Gain on aircraft sales, trading and other activity	(33,898)	(56,457)	(19,234)
Changes in operating assets and liabilities:
Other assets	4,162	(1,191)	(2,653)
Accrued interest and other payables	16,635	45,738	39,507
Rentals received in advance	15,608	14,357	20,383
Net cash provided by operating activities	839,795	769,018	654,213
Investing Activities
Acquisition of flight equipment under operating lease	(2,088,646)	(1,568,748)	(1,329,619)
Payments for deposits on flight equipment purchases	(597,170)	(601,307)	(828,839)
Proceeds from aircraft sales, trading and other activity	752,747	603,849	97,748
Acquisition of furnishings, equipment and other assets	(219,732)	(239,451)	(125,184)
Net cash used in investing activities	(2,152,801)	(1,805,657)	(2,185,894)
Financing Activities
Issuance of common stock upon exercise of options	60	944
Cash dividends paid	(16,405)	(12,243)	(7,608)
Tax withholdings on stock-based compensation	(5,302)	(18,089)	(12,664)
Tax benefits from stock-based compensation arrangements		7,011	2,115
Net change in unsecured revolving facilities	151,000	(239,000)	388,000
Proceeds from debt financings	1,232,384	1,663,120	1,608,854
Payments in reduction of debt financings	(328,248)	(577,212)	(531,831)
Net change in restricted cash	(9,059)	79,839	18,999
Debt issuance costs	(4,518)	(7,975)	(37,535)
Security deposits and maintenance reserve receipts	218,380	185,639	172,662
Security deposits and maintenance reserve disbursements	(51,430)	(32,749)	(29,227)
Net cash provided by financing activities	1,186,862	1,049,285	1,571,765
Net increase (decrease) in cash	(126,144)	12,646	40,084
Cash and cash equivalents at beginning of period	282,819	270,173	230,089
Cash and cash equivalents at end of period	156,675	282,819	270,173
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest, including capitalized interest of $40,118, $42,775 and $32,659 at December 31, 2015, 2014 and 2013, respectively	259,968	211,345	188,464
Supplemental Disclosure of Noncash Activities
Buyer furnished equipment, capitalized interest, deposits on flight equipment purchases and seller financing applied to acquisition of flight equipment and other assets applied to payments for deposits on flight equipment purchases	944,469	756,286	459,432
Cash dividends declared, not yet paid	$ 5,129	$ 4,096	$ 3,055