Goodwill - Carrying Amount of Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)
Changes in the carrying amount of goodwill
Balance at January 1, 2015	$ 267,587
Effect of foreign exchange rate changes	(8,279)
Balance at September 30, 2015	259,308
International
Changes in the carrying amount of goodwill
Balance at January 1, 2015	133,906
Effect of foreign exchange rate changes	(8,279)
Balance at September 30, 2015	125,627
North America
Changes in the carrying amount of goodwill
Balance at January 1, 2015	133,681
Effect of foreign exchange rate changes	0
Balance at September 30, 2015	$ 133,681