Basis of Presentation - Additional Information (Detail) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018 USD ($) ClassOfCommonStock Segment $ / shares	Dec. 31, 2017 USD ($) ClassOfCommonStock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of operating segments | Segment	3
Number of class of common stock outstanding | ClassOfCommonStock	1	1
Non-current deferred rent combined with other non-current assets and liabilities	$ 37,152	$ 37,354
Reclassifications [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Accrued airline revenue share combined with accrued liabilities	918
Current deferred rent combined with accrued liabilities	11
Non-current deferred rent combined with other non-current assets and liabilities	359
Estimated Useful Lives [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Increases in depreciation expense	4,300
Decrease in cost of service revenue	$ 1,000
Increase in net loss per basic and fully diluted share | $ / shares	$ 0.04