Goodwill - Changes in Carrying Amount (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Changes in the carrying amount of goodwill
Balance at the beginning of the period	$ 267,587	$ 281,714
Effect of foreign exchange rate changes	(10,851)	(15,409)
Acquisition		1,282
Balance at the end of the period	256,736	267,587
International
Changes in the carrying amount of goodwill
Balance at the beginning of the period	133,906	148,033
Effect of foreign exchange rate changes	(10,851)	(15,409)
Acquisition		1,282
Balance at the end of the period	123,055	133,906
North America
Changes in the carrying amount of goodwill
Balance at the beginning of the period	133,681	133,681
Effect of foreign exchange rate changes	0	0
Acquisition		0
Balance at the end of the period	$ 133,681	$ 133,681