STOCKHOLDERS' EQUITY: (Details 4) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 Employee Stock Purchase Plan USD ($) Y	Dec. 31, 2011 Employee Stock Purchase Plan USD ($)	Dec. 31, 2010 Employee Stock Purchase Plan USD ($)	Dec. 31, 2012 New Employee Stock Purchase Plan USD ($) Y	Dec. 31, 2011 New Employee Stock Purchase Plan USD ($)	Dec. 31, 2010 New Employee Stock Purchase Plan USD ($)	Dec. 31, 2010 New Employee Stock Purchase Plan MXN
Information related to compensation cost
Stock based compensation expenses	$ 2.1	$ 2.1	$ 2.1
Unrecognized compensation expenses	$ 4.2			$ 3.2
Period over which unrecognized compensation expense expected to be recognized (in years)	2			6
Stock award activity, Shares
Outstanding shares at the beginning of the period	7,270,341	10,920,693		3,807,146	3,901,901
Granted (in shares)					51,923
Exercised (in shares)	(220,430)	(3,402,855)		(772,850)
Forfeited (in shares)	(94,339)	(247,497)		(89,554)	(146,678)
Outstanding shares at the end of the period	6,955,572	7,270,341	10,920,693	2,944,742	3,807,146	3,901,901	3,901,901
Unit Weighted Average Grant Date Fair Value
Outstanding shares at the beginning of the period (in dollars per share)	$ 1.16	$ 1.16		$ 2.05	$ 2.05
Granted (in dollars per share)					$ 2.05
Exercised (in dollars per share)	$ 1.16	$ 1.16		$ 2.05
Forfeited (in dollars per share)	$ 1.16	$ 1.16		$ 2.05	$ 2.05
Outstanding shares at the end of the period (in dollars per share)	$ 1.16	$ 1.16	$ 1.16	$ 2.05	$ 2.05	$ 2.05
Purchase price for initial subscription (per share data)						$ 2.05	26.51