Summary of Significant Accounting Policies - Concentration of Credit Risk (Details)	12 Months Ended
	Dec. 31, 2015 USD ($) bank	Dec. 31, 2014 USD ($) bank	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)
Cash and Cash Equivalents [Line Items]
Number of "Triple A" rated money market funds with cash, cash equivalent and restricted cash held on deposit | bank		2
Number of global banks with cash, cash equivalent and restricted cash held on deposit | bank	4	3
Maximum investment limit in any one mutual fund	$ 50,000
Maximum investment limit in any one financial institution	75,000
Cash, cash equivalent and restricted cash	128,381,000	$ 159,793,000
Cash and cash equivalents	128,381,000	125,933,000	$ 120,526,000	$ 243,415,000
Money Market Funds
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents		36,828,000
Time Deposits
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 18,645,000	$ 16,204,000