Fair Value Measurement - Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Cash Equivalents, at Carrying Value [Abstract]
Cash equivalents	$ 35,076	$ 62,024	$ 23,975
Cash	126,142	190,812	164,172
Total cash and cash equivalents	$ 161,218	$ 252,836	$ 188,147	$ 255,961