Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES [Abstract]
Accrued expenses	$ 305,969	$ 301,390
Accrued amounts due to mobile operators and other content providers	79,155	92,291
Money transfer settlement obligations	341,073	343,613
Derivative liabilities	25,829	22,495
Accrued expenses and other current liabilities	$ 752,295	$ 759,789