Acquisitions (Narrative) (Details) - USD ($)	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2017	Feb. 22, 2017	Oct. 11, 2016
Business Acquisition [Line Items]
Goodwill		$ 304,032,000	$ 320,848,000
Package Concierge
Business Acquisition [Line Items]
Aggregate consideration for acquisition	$ 18,917,000
Goodwill				$ 16,931,000
Working capital adjustment payable	$ 67,000
Nexus Corporation
Business Acquisition [Line Items]
Aggregate consideration for acquisition		23,762,000
Goodwill					$ 11,451,000
Working capital adjustment payable		$ 1,000,000	$ 167,000