Description of Business and Summary of Significant Accounting Policies (Finite-lived Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible assets, gross	$ 116,010		$ 115,791
Finite-lived intangible assets, accumulated amortization	(67,451)		(64,343)
Finite-lived intangible assets, net	48,559		51,448
Amortization of Acquired Intangible Assets	3,000	$ 2,000
Customer Relationships [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible assets, gross	$ 80,219		80,070
Customer Relationships [Member] | Minimum [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible asset, useful life	7 years
Customer Relationships [Member] | Maximum [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible asset, useful life	20 years
Developed technology [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible assets, gross	$ 19,216		19,176
Developed technology [Member] | Minimum [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible asset, useful life	3 years
Developed technology [Member] | Maximum [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible asset, useful life	12 years
Dealer Networks [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible assets, gross	$ 6,325		6,315
Dealer Networks [Member] | Minimum [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible asset, useful life	15 years
Dealer Networks [Member] | Maximum [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible asset, useful life	20 years
Airport Contracts [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible assets, gross	$ 4,761		4,752
Airport Contracts [Member] | Maximum [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible asset, useful life	9 years
Store Networks [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible assets, gross	$ 822		821
Store Networks [Member] | Maximum [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible asset, useful life	5 years
Brand [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible assets, gross	$ 866		864
Brand [Member] | Maximum [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible asset, useful life	15 years
Trademarks [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible assets, gross	$ 2,685		2,677
Trademarks [Member] | Minimum [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible asset, useful life	3 years
Trademarks [Member] | Maximum [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible asset, useful life	15 years
Backlog [Member] | Maximum [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible asset, useful life	1 year 2 months
Non-compete agreements [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible assets, gross	$ 764		764
Non-compete agreements [Member] | Maximum [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible asset, useful life	5 years
Backlog [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible assets, gross	$ 140		140
Database [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible assets, gross	$ 212		212
Database [Member] | Maximum [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Finite-lived intangible asset, useful life	10 years
Customer Relationships [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line items]
Indefinite-lived intangible assets	$ 42,055		$ 42,055