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Acquisitions (Narrative) (Details) - USD ($) $ in Thousands			3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Feb. 22, 2017	Oct. 11, 2016
Business Acquisition [Line Items]
Goodwill	$ 320,411	$ 304,032	$ 320,411
Acquisition related costs			102	$ 31
Package Concierge
Business Acquisition [Line Items]
Aggregate consideration for acquisition	18,892
Goodwill					$ 16,710
Nexus Corporation
Business Acquisition [Line Items]
Aggregate consideration for acquisition		23,762
Goodwill						$ 11,451
Working capital adjustment payable	$ 168	$ 1,000	$ 168

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- Definition

Business Combination, Working Capital Adjustment Payable

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- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=73531572&loc=d3e1043-128460

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- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

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-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

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-Name Accounting Standards Codification
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-SubTopic 30
-Section 30
-Paragraph 8
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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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-URI http://asc.fasb.org/extlink&oid=64834752&loc=SL49117168-202975

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