Description of Business and Summary of Significant Accounting Policies Description of Business and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	3 Months Ended												12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Finite-Lived and Indefinite Lived Intangible Lived Assets [Line Items]
Right-of-use assets	$ 19,544,000				$ 0								$ 19,544,000	$ 0
Restricted Cash [Abstract]
Restricted cash	35,051,000				8,317,000				$ 4,040,000				35,051,000	8,317,000	$ 4,040,000
Impairment of intangible assets, indefinite-lived (excluding goodwill)													0	0	0
Goodwill, impairment loss													0	0	0
Operating revenue	146,183,000	$ 147,233,000	$ 144,275,000	$ 142,924,000	136,327,000	$ 128,643,000	$ 124,626,000	$ 108,230,000	$ 104,681,000	$ 92,800,000	$ 87,387,000	$ 79,103,000	580,615,000	497,826,000	$ 363,971,000
Operating lease, liability	19,151,000												$ 19,151,000
Minimum
Restricted Cash [Abstract]
Capitalized direct response advertising costs, amortization period															12 months
Minimum | Customer relationships
Restricted Cash [Abstract]
Finite-lived intangible asset, useful life													7 years
Minimum | Developed technology
Restricted Cash [Abstract]
Finite-lived intangible asset, useful life													3 years
Minimum | Dealer networks
Restricted Cash [Abstract]
Finite-lived intangible asset, useful life													15 years
Minimum | Trademarks
Restricted Cash [Abstract]
Finite-lived intangible asset, useful life													3 years
Maximum
Restricted Cash [Abstract]
Capitalized direct response advertising costs, amortization period															24 months
Maximum | Customer relationships
Restricted Cash [Abstract]
Finite-lived intangible asset, useful life													20 years
Maximum | Developed technology
Restricted Cash [Abstract]
Finite-lived intangible asset, useful life													12 years
Maximum | Dealer networks
Restricted Cash [Abstract]
Finite-lived intangible asset, useful life													20 years
Maximum | Trademarks
Restricted Cash [Abstract]
Finite-lived intangible asset, useful life													15 years
Maximum | Non-compete agreements
Restricted Cash [Abstract]
Finite-lived intangible asset, useful life													5 years
Maximum | Database
Restricted Cash [Abstract]
Finite-lived intangible asset, useful life													10 years
Maximum | Airport Contracts
Restricted Cash [Abstract]
Finite-lived intangible asset, useful life													9 years
Maximum | Store Networks
Restricted Cash [Abstract]
Finite-lived intangible asset, useful life													5 years
Maximum | Brand
Restricted Cash [Abstract]
Finite-lived intangible asset, useful life													15 years
Recurring | Certificates of Deposit
Restricted Cash [Abstract]
Available-for-sale securities, noncurrent	50,000				680,000								$ 50,000	680,000
Recurring | Mutual Funds
Restricted Cash [Abstract]
Available-for-sale securities	$ 0				0								0	0
INDIA
Restricted Cash [Abstract]
Operating revenue					$ 65,900,000								$ 320,000,000	$ 217,500,000	$ 64,300,000
Accounting Standards Update 2016-02 | Minimum
Finite-Lived and Indefinite Lived Intangible Lived Assets [Line Items]
Right-of-use assets																$ 140,000,000
Restricted Cash [Abstract]
Operating lease, liability																140,000,000
Accounting Standards Update 2016-02 | Maximum
Finite-Lived and Indefinite Lived Intangible Lived Assets [Line Items]
Right-of-use assets																150,000,000
Restricted Cash [Abstract]
Operating lease, liability																$ 150,000,000