Fair Value Measurement - Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Cash Equivalents, at Carrying Value [Abstract]
Cash equivalents	$ 46,094	$ 62,024	$ 54,709
Cash	152,204	190,812	184,694
Total cash and cash equivalents	$ 198,298	$ 252,836	$ 239,403	$ 255,961