Summary of Business and Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) reporting_unit segment $ / shares	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2017 USD ($) $ / shares	Jan. 01, 2020 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of business segments | segment	3
Advertising expense	$ 19,000,000	$ 19,000,000	$ 18,000,000
Allowance for doubtful accounts receivable	58,000,000	45,000,000
Depreciation and amortization of property and equipment	295,000,000	288,000,000	256,000,000
Amortization	39,444,000	41,724,000	40,131,000
Capitalized software development	$ 89,000,000	252,000,000	251,000,000
Number of reportable segments | reporting_unit	3
Goodwill impairment charges	$ 0	$ 0	$ 0
Dividend per common share (in dollars per share) | $ / shares	$ 0.56	$ 0.56	$ 0.56
Retained deficit	$ (763,482,000)	$ (768,566,000)
Costs to Fulfill Contracts
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Amortization of capitalized implementation costs, included in depreciation and amortization	39,444,000	37,904,000	$ 40,000,000
Software developed for internal use
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Amortization	241,000,000	236,000,000	$ 203,000,000
Commercial Air Travel | Accounts receivable, net
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable, net	$ 375,000,000	$ 334,000,000
Commercial Air Travel | Accounts receivable, net | Customer Concentration Risk
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Concentration risk percentage	82.00%	81.00%
Commercial Air Travel | ACH Payment | Customer Concentration Risk
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Concentration risk percentage	59.00%
Commercial Air Travel | Air Revenue | Customer Concentration Risk
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Concentration risk percentage	89.00%
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Expected life of service contracts with significant travel agency customers	3 years
Amortization period	2 years
Amortization of capitalized implementation costs	3 years
Minimum | Accounting Standards Update 2016-13 | Subsequent event | Forecast
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained deficit				$ 13,000,000
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Expected life of service contracts with significant travel agency customers	5 years
Amortization period	30 years
Amortization of capitalized implementation costs	10 years
Maximum | Accounting Standards Update 2016-13 | Subsequent event | Forecast
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained deficit				$ (23,000,000)