Goodwill (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Goodwill [Line Items]
Balance at beginning of period	$ 370,066us-gaap_Goodwill	$ 240,314us-gaap_Goodwill
Effect of foreign currency exchange rates	(16,426)us-gaap_GoodwillTranslationAdjustments	1,178us-gaap_GoodwillTranslationAdjustments
Goodwill acquired through acquisitions	235,897us-gaap_GoodwillPeriodIncreaseDecrease	128,574us-gaap_GoodwillPeriodIncreaseDecrease
Balance at end of period	589,537us-gaap_Goodwill	370,066us-gaap_Goodwill
Americas [Member]
Goodwill [Line Items]
Balance at beginning of period	264,735	168,202
Effect of foreign currency exchange rates	1,804
Goodwill acquired through acquisitions	72,872	96,533
Balance at end of period	339,411	264,735
Europe [Member]
Goodwill [Line Items]
Balance at beginning of period	71,155	40,276
Effect of foreign currency exchange rates	(17,238)	2,145
Goodwill acquired through acquisitions	163,025	28,734
Balance at end of period	216,942	71,155
Asia Pacific [Member]
Goodwill [Line Items]
Balance at beginning of period	34,176	31,836
Effect of foreign currency exchange rates	(992)	(967)
Goodwill acquired through acquisitions		3,307
Balance at end of period	$ 33,184	$ 34,176

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

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-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

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