Business Acquisitions (Intangible Assets Acquired) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Total acquired intangible assets, Fair Value	$ 14,577	$ 11,267
Acquired intangible assets, Weighted Average Useful Life (in years)	9 years 2 months 5 days	17 years 6 months 25 days
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Total acquired intangible assets, Fair Value	$ 7,342	$ 518
Acquired intangible assets, Weighted Average Useful Life (in years)	11 years 8 months	10 years
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Total acquired intangible assets, Fair Value	$ 3,726	$ 0
Acquired intangible assets, Weighted Average Useful Life (in years)	5 years	0 days
Trademarks
Acquired Finite-Lived Intangible Assets [Line Items]
Total acquired intangible assets, Fair Value	$ 0	$ 10,499
Acquired intangible assets, Weighted Average Useful Life (in years)	0 days	17 years 11 months 12 days
Airport Contracts
Acquired Finite-Lived Intangible Assets [Line Items]
Total acquired intangible assets, Fair Value	$ 4,896	$ 0
Acquired intangible assets, Weighted Average Useful Life (in years)	9 years	0 days
Store Networks
Acquired Finite-Lived Intangible Assets [Line Items]
Total acquired intangible assets, Fair Value	$ 846	$ 0
Acquired intangible assets, Weighted Average Useful Life (in years)	9 years	0 days
Brand
Acquired Finite-Lived Intangible Assets [Line Items]
Total acquired intangible assets, Fair Value	$ 369	$ 0
Acquired intangible assets, Weighted Average Useful Life (in years)	4 years	0 days
Final Allocation Adjustment | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Total acquired intangible assets, Fair Value	$ (2,602)	$ 250
Acquired intangible assets, Weighted Average Useful Life (in years)	0 days	0 days