Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Line Items]
Balance at beginning of period	$ 187,875	$ 589,537
Acquisitions and adjustments	52	55,262
Impairment of goodwill	0	(443,659)	$ 0
Effect of foreign currency exchange rates	(6,697)	(13,265)
Balance at end of period	181,230	187,875	589,537
Americas [Member]
Goodwill [Line Items]
Balance at beginning of period		339,411
Acquisitions and adjustments		47,452
Impairment of goodwill	(382,271)	(382,271)
Effect of foreign currency exchange rates		(4,592)
Balance at end of period			339,411
Other EMEA [Member]
Goodwill [Line Items]
Balance at beginning of period	150,521	216,942
Acquisitions and adjustments		2,602
Acquisitions and adjustments	(137)
Impairment of goodwill	(61,388)	(61,388)
Effect of foreign currency exchange rates	(5,413)	(7,635)
Balance at end of period	144,971	150,521	216,942
Asia Pacific [Member]
Goodwill [Line Items]
Balance at beginning of period	37,354	33,184
Acquisitions and adjustments	189	5,208
Impairment of goodwill
Effect of foreign currency exchange rates	(1,284)	(1,038)
Balance at end of period	$ 36,259	$ 37,354	$ 33,184