FAIR VALUE MEASUREMENT, Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2013 Fair Value Measured on a Recurring Basis [Member]	Dec. 31, 2012 Fair Value Measured on a Recurring Basis [Member]	Jun. 30, 2013 Fair Value Measured on a Recurring Basis [Member] Level I [Member]	Dec. 31, 2012 Fair Value Measured on a Recurring Basis [Member] Level I [Member]	Jun. 30, 2013 Fair Value Measured on a Recurring Basis [Member] Level II [Member]	Dec. 31, 2012 Fair Value Measured on a Recurring Basis [Member] Level II [Member]	Jun. 30, 2013 Fair Value Measured on a Recurring Basis [Member] Level III [Member]	Dec. 31, 2012 Fair Value Measured on a Recurring Basis [Member] Level III [Member]
Assets [Abstract]
Money market funds			$ 362,845	$ 250,695	$ 362,845	$ 250,695	$ 0	$ 0	$ 0	$ 0
Investment securities			141	122	141	122	0	0	0	0
Investment securities pledged as collateral			899,482	802,834	899,482	802,834	0	0	0	0
Prepaid forward contracts			18,252	3,143	0	0	18,252	3,143	0	0
Liabilities under derivative contracts [Abstract]
Prepaid forward contracts			119,462	148,263	0	0	119,462	148,263	0	0
Impairment charges related to nonfinancial assets	$ 9,231	$ 10,561