Acquisitions (Schedule of Acquired Intangible Assets) (Details) $ in Thousands	Feb. 22, 2017 USD ($)
Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	10 years
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	7 years
Package Concierge
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value, finite-lived intangible assets acquired	$ 3,600
Package Concierge | Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value, finite-lived intangible assets acquired	1,300
Package Concierge | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value, finite-lived intangible assets acquired	1,700
Package Concierge | Trademarks
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value, finite-lived intangible assets acquired	$ 600