Revenue Recognition (Tables)

12 Months Ended

Dec. 31, 2018

Revenue from Contract with Customer [Abstract]

Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]

The following tables show adjustments made due to the adoption of ASU 2014-09 on the December 31, 2017 and 2016 statements of operations. Previously reported results were derived from audited financial statements included in Company's Annual Report on Form 10-K for the fiscal years ended December 31, 2017 and December 31, 2016, as applicable.

	Year Ended December 31, 2017
	(in thousands, except share and per-share data)
	As Reported			Topic 606 Adjustment			As Adjusted
Operating revenues:
Passenger	$	1,366,034		$	1,206,853		$	2,572,887
Other	1,281,632			(1,210,967		)	70,665
Total operating revenues	2,647,666			(4,114		)	2,643,552
Operating expenses:
Aircraft fuel	615,581			—			615,581
Salaries, wages and benefits	527,959			—			527,959
Aircraft rent	205,852			—			205,852
Landing fees and other rents	180,655			—			180,655
Depreciation and amortization	140,152			—			140,152
Maintenance, materials and repairs	110,439			—			110,439
Distribution	113,620			(148		)	113,472
Special charges	12,629			—			12,629
Loss on disposal of assets	4,168			—			4,168
Other operating	347,820			—			347,820
Total operating expenses	2,258,875			(148		)	2,258,727
Operating income	388,791			(3,966		)	384,825
Other (income) expense:
Interest expense	57,302			—			57,302
Capitalized interest	(13,793		)	—			(13,793		)
Interest income	(8,736		)	—			(8,736		)
Other expense	366			—			366
Total other (income) expense	35,139			—			35,139
Income before income taxes	353,652			(3,966		)	349,686
Provision (benefit) for income taxes	(66,954		)	1,118			(65,836		)
Net income	$	420,606		$	(5,084	)	$	415,522
Basic earnings per share	$	6.08		$	(0.07	)	$	6.00
Diluted earnings per share	$	6.06		$	(0.07	)	$	5.99

	Year Ended December 31, 2016
	(in thousands, except share and per-share data)
	As Reported			Topic 606 Adjustment			As Adjusted
Operating revenues:
Passenger	$	1,200,621		$	1,057,180		$	2,257,801
Other	1,121,335			(1,059,115		)	62,220
Total operating revenues	2,321,956			(1,935		)	2,320,021
Operating expenses:
Salaries, wages and benefits	472,471			—			472,471
Aircraft fuel	447,553			—			447,553
Aircraft rent	201,675			—			201,675
Landing fees and other rents	151,679			—			151,679
Depreciation and amortization	101,136			—			101,136
Maintenance, materials and repairs	98,587			—			98,587
Distribution	96,627			268			96,895
Special charges	37,189			—			37,189
Loss on disposal of assets	4,187			—			4,187
Other operating	267,191			—			267,191
Total operating expenses	1,878,295			268			1,878,563
Operating income	443,661			(2,203		)	441,458
Other (income) expense:
Interest expense	41,654			—			41,654
Capitalized interest	(12,705		)	—			(12,705		)
Interest income	(5,276		)	—			(5,276		)
Other expense	528			—			528
Total other (income) expense	24,201			—			24,201
Income before income taxes	419,460			(2,203		)	417,257
Provision (benefit) for income taxes	154,581			(807		)	153,774
Net income	$	264,879		$	(1,396	)	$	263,483
Basic earnings per share	$	3.77		$	(0.02	)	$	3.75
Diluted earnings per share	$	3.76		$	(0.02	)	$	3.74

The following table shows adjusted balances after the adoption of ASU 2014-09 on the quarterly statements of operations for each quarter of 2017.

	For the Quarter Ended
	March 31, 2017			June 30, 2017			September 30, 2017			December 31, 2017
	(unaudited)
	(in thousands, except share and per-share data)
Operating revenues:
Passenger	$	572,287		$	680,880		$	669,072		$	650,647
Other	17,670			19,305			18,155			15,535
Total operating revenues	589,957			700,185			687,227			666,182
Operating expenses:
Aircraft fuel	139,782			142,294			158,300			175,205
Salaries, wages and benefits	127,138			129,892			134,114			136,815
Aircraft rent	57,070			52,566			53,396			42,820
Landing fees and other rents	40,448			45,592			48,498			46,117
Depreciation and amortization	31,509			35,331			36,840			36,472
Maintenance, materials and repairs	26,312			28,985			26,176			28,966
Distribution	25,772			29,835			29,695			28,170
Special charges	4,776			—			7,853			—
Loss on disposal of assets	1,105			1,493			516			1,054
Other operating	77,703			102,885			87,965			79,267
Total operating expenses	531,615			568,873			583,353			574,886
Operating income	58,342			131,312			103,874			91,296
Other (income) expense:
Interest expense	12,473			13,746			15,018			16,065
Capitalized interest	(3,580		)	(3,342		)	(3,203		)	(3,668		)
Interest income	(1,313		)	(1,828		)	(2,605		)	(2,990		)
Other expense	3			104			114			145
Total other (income) expense	7,583			8,680			9,324			9,552
Income before income taxes	50,759			122,632			94,550			81,744
Provision (benefit) for income taxes	19,498			45,391			34,506			(165,231		)
Net income	$	31,261		$	77,241		$	60,044		$	246,975
Basic earnings per share	$	0.45		$	1.11		$	0.87		$	3.59
Diluted earnings per share	$	0.45		$	1.11		$	0.86		$	3.58

The following table shows quarterly adjustments made due to the adoption of ASU 2014-09 on the statements of operations for 2017.

				Adjustments for the Quarter Ended
	Full Year 2017 As Reported			March 31, 2017			June 30, 2017			September 30, 2017			December 31, 2017			Full Year 2017 Adjusted
	(unaudited)
	(in thousands, except share and per-share data)
Operating revenues:
Passenger	$	1,366,034		$	272,525		$	308,959		$	312,865		$	312,504		$	2,572,887
Other	1,281,632			(274,314		)	(310,455		)	(312,869		)	(313,329		)	70,665
Total operating revenues	2,647,666			(1,789		)	(1,496		)	(4		)	(825		)	2,643,552
Operating expenses:
Aircraft fuel	615,581			—			—			—			—			615,581
Salaries, wages and benefits	527,959			—			—			—			—			527,959
Aircraft rent	205,852			—			—			—			—			205,852
Landing fees and other rents	180,655			—			—			—			—			180,655
Depreciation and amortization	140,152			—			—			—			—			140,152
Maintenance, materials and repairs	110,439			—			—			—			—			110,439
Distribution	113,620			(726		)	(73		)	226			425			113,472
Special charges	12,629			—			—			—			—			12,629
Loss on disposal of assets	4,168			—			—			—			—			4,168
Other operating	347,820			—			—			—			—			347,820
Total operating expenses	2,258,875			(726		)	(73		)	226			425			2,258,727
Operating income	388,791			(1,063		)	(1,423		)	(230		)	(1,250		)	384,825
Other (income) expense:
Interest expense	57,302			—			—			—			—			57,302
Capitalized interest	(13,793		)	—			—			—			—			(13,793		)
Interest income	(8,736		)	—			—			—			—			(8,736		)
Other expense	366			—			—			—			—			366
Total other (income) expense	35,139			—			—			—			—			35,139
Income before income taxes	353,652			(1,063		)	(1,423		)	(230		)	(1,250		)	349,686
Provision (benefit) for income taxes	(66,954		)	(389		)	(522		)	(84		)	2,113			(65,836		)
Net income	$	420,606		$	(674	)	$	(901	)	$	(146	)	$	(3,363	)	$	415,522
Basic earnings per share	$	6.08		$	(0.01	)	$	(0.01	)	$	—		$	(0.05	)	$	6.00
Diluted earnings per share	$	6.06		$	(0.01	)	$	(0.01	)	$	—		$	(0.05	)	$	5.99

The following tables show adjustments made due to the adoption of ASU 2014-09 on the December 31, 2017 and 2016 balance sheets. Previously reported results were derived from audited financial statements included in Company's Annual Report on Form 10-K for the fiscal years ended December 31, 2017 and December 31, 2016, as applicable.

	December 31, 2017
	(in thousands)
	As Reported			Topic 606 Adjustment			As Adjusted
Assets
Current assets:
Cash and cash equivalents	$	800,849		$	—		$	800,849
Short-term investment securities	100,937			—			100,937
Accounts receivable, net	49,323			—			49,323
Aircraft maintenance deposits, net	175,615			—			175,615
Income tax receivable	69,844			—			69,844
Prepaid expenses and other current assets	83,692			1,850			85,542
Total current assets	1,280,260			1,850			1,282,110
Property and equipment:
Flight equipment	2,291,110			—			2,291,110
Ground property and equipment	155,166			—			155,166
Less accumulated depreciation	(207,808		)	—			(207,808		)
	2,238,468			—			2,238,468
Deposits on flight equipment purchase contracts	253,687			—			253,687
Long-term aircraft maintenance deposits	150,617			—			150,617
Deferred heavy maintenance, net	99,915			—			99,915
Other long-term assets	121,003			—			121,003
Total assets	$	4,143,950		$	1,850		$	4,145,800
Liabilities and shareholders’ equity
Current liabilities:
Accounts payable	$	22,822		$	—		$	22,822
Air traffic liability	246,404			17,307			263,711
Current maturities of long-term debt	115,430			—			115,430
Other current liabilities	262,370			—			262,370
Total current liabilities	647,026			17,307			664,333
Long-term debt, less current maturities	1,387,498			—			1,387,498
Deferred income taxes	313,140			(4,326		)	308,814
Deferred gains and other long-term liabilities	19,205			3,376			22,581
Shareholders’ equity:
Common stock: Common stock, $0.0001 par value, 240,000,000 shares authorized at December 31, 2017; 69,770,795 issued and 68,196,964 outstanding as of December 31, 2017	7			—			7
Additional paid-in-capital	360,153			—			360,153
Treasury stock, at cost: 1,573,831 shares as of December 31, 2017	(65,854		)	—			(65,854		)
Retained earnings	1,484,239			(14,507		)	1,469,732
Accumulated other comprehensive income (loss)	(1,464		)	—			(1,464		)
Total shareholders’ equity	1,777,081			(14,507		)	1,762,574
Total liabilities and shareholders’ equity	$	4,143,950		$	1,850		$	4,145,800

	December 31, 2016
	(in thousands)
	As Reported			Topic 606 Adjustment			As Adjusted
Assets
Current assets:
Cash and cash equivalents	$	700,900		$	—		$	700,900
Short-term investment securities	100,155			—			100,155
Accounts receivable, net	41,136			—			41,136
Aircraft maintenance deposits, net	87,035			—			87,035
Income tax receivable	—			—			—
Prepaid expenses and other current assets	46,619			1,702			48,321
Total current assets	975,845			1,702			977,547
Property and equipment:
Flight equipment	1,461,525			—			1,461,525
Ground property and equipment	126,206			—			126,206
Less accumulated depreciation	(122,509		)	—			(122,509		)
	1,465,222			—			1,465,222
Deposits on flight equipment purchase contracts	325,688			—			325,688
Long-term aircraft maintenance deposits	199,415			—			199,415
Deferred heavy maintenance, net	75,534			—			75,534
Other long-term assets	110,223			—			110,223
Total assets	$	3,151,927		$	1,702		$	3,153,629
Liabilities and shareholders’ equity
Current liabilities:
Accounts payable	$	15,193		$	—		$	15,193
Air traffic liability	206,392			13,792			220,184
Current maturities of long-term debt	84,354			—			84,354
Other current liabilities	226,011			—			226,011
Total current liabilities	531,950			13,792			545,742
Long-term debt, less current maturities	897,359			—			897,359
Deferred income taxes	308,143			(5,443		)	302,700
Deferred gains and other long-term liabilities	19,868			2,776			22,644
Shareholders’ equity:
Common stock: Common stock, $0.0001 par value, 240,000,000 shares authorized at December 31, 2016; 73,549,872 issued and 69,326,202 outstanding as of December 31, 2016	7			—			7
Additional paid-in-capital	551,004			—			551,004
Treasury stock, at cost: 4,223,670 shares as of December 31, 2016	(218,692		)	—			(218,692		)
Retained earnings	1,063,633			(9,423		)	1,054,210
Accumulated other comprehensive income (loss)	(1,345		)	—			(1,345		)
Total shareholders’ equity	1,394,607			(9,423		)	1,385,184
Total liabilities and shareholders’ equity	$	3,151,927		$	1,702		$	3,153,629