CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Operating Activities
Net income	$ 374,925	$ 253,391	$ 255,998
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of flight equipment	452,682	397,760	336,657
Share-based Compensation	16,941	17,022	16,048
Deferred taxes	205,313	138,608	137,107
Tax benefits from stock-based compensation arrangements			(7,011)
Amortization of discounts and debt issuance costs	30,942	30,507	27,772
Gain on aircraft sales, trading and other activity	(61,494)	(33,898)	(56,457)
Changes in operating assets and liabilities:
Other assets	(53,114)	4,162	(1,191)
Accrued interest and other payables	45,983	16,635	45,738
Rentals received in advance	7,900	15,608	14,357
Net cash provided by operating activities	1,020,078	839,795	769,018
Investing Activities
Acquisition of flight equipment under operating lease	(1,914,093)	(2,088,646)	(1,568,748)
Payments for deposits on flight equipment purchases	(868,091)	(597,170)	(601,307)
Proceeds from aircraft sales, trading and other activity	988,040	752,747	603,849
Acquisition of furnishings, equipment and other assets	(211,372)	(219,732)	(239,451)
Net cash used in investing activities	(2,005,516)	(2,152,801)	(1,805,657)
Financing Activities
Issuance of common stock upon exercise of options	20	60	944
Cash dividends paid	(20,555)	(16,405)	(12,243)
Tax withholdings on stock-based compensation	(5,890)	(5,302)	(18,089)
Tax benefits from stock-based compensation arrangements			7,011
Net change in unsecured revolving facilities	46,000	151,000	(239,000)
Proceeds from debt financings	2,021,966	1,232,384	1,663,120
Payments in reduction of debt financings	(1,093,910)	(328,248)	(577,212)
Net change in restricted cash	528	(9,059)	79,839
Debt issuance costs	(5,042)	(4,518)	(7,975)
Security deposits and maintenance reserve receipts	218,754	218,380	185,639
Security deposits and maintenance reserve disbursements	(58,306)	(51,430)	(32,749)
Net cash provided by financing activities	1,103,565	1,186,862	1,049,285
Net increase (decrease) in cash	118,127	(126,144)	12,646
Cash and cash equivalents at beginning of period	156,675	282,819	270,173
Cash and cash equivalents at end of period	274,802	156,675	282,819
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest, including capitalized interest of $40,883, $40,118 and $42,775 at December 31, 2016, 2015 and 2014, respectively	293,969	259,968	211,345
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	873,828	944,469	756,286
Cash dividends declared, not yet paid	$ 7,714	$ 5,129	$ 4,096