BENEFIT PLANS: (Details 2) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Post retirement defined benefit plan | Expatriate Plan
Benefit plans
Net asset value (in dollars per share)	$ 1.00
Target duration of funds invested in publicly traded, investment grade securities	1 year 6 months
Maturity period of 4.0% coupon on which Bond Fund has an overweight position	30 years
Interest rate of coupon on which Bond Fund is overweight (as a percent)	4.00%
Assumptions used to determine the pension obligation and seniority premiums as of year-end and the net cost in the ensuing year
Discount rate (as a percent)	4.25%	3.35%	3.95%
Expected long-term rate of return on plan asset (as a percent)	4.50%	4.50%	4.50%
Post retirement defined benefit plan | Mexican Health Plan
Assumptions used to determine the pension obligation and seniority premiums as of year-end and the net cost in the ensuing year
Discount rate (as a percent)	7.10%	6.50%	7.50%
Expected long-term rate of return on plan asset (as a percent)	7.10%	6.50%	7.50%
Number of financial institutions managing plan assets	3
Plan obligations as a percentage of benefit obligation	30.00%
Asset allocation (as a percent)	100.00%	100.00%
Expected employer contribution in next fiscal year	$ 2.4
Post retirement defined benefit plan | Minimum | Expatriate Plan
Benefit plans
Period of breakevens for Treasuries/Agencies, BlackRock is overweight	5 years
Post retirement defined benefit plan | Minimum | Fannie | Expatriate Plan
Benefit plans
Period of Bond Fund for which the BlackRock has a small overweight to agency mortgages	5 years
Post retirement defined benefit plan | Maximum | Expatriate Plan
Benefit plans
Period of breakevens for Treasuries/Agencies, BlackRock is overweight	10 years
Post retirement defined benefit plan | Maximum | Fannie | Expatriate Plan
Benefit plans
Period of Bond Fund for which the BlackRock has a small overweight to agency mortgages	10 years
Post retirement defined benefit plan | Parent Company (Grupo Mexico) common shares | Mexican Health Plan
Assumptions used to determine the pension obligation and seniority premiums as of year-end and the net cost in the ensuing year
Asset allocation (as a percent)	74.00%
Post retirement defined benefit plan | Equity securities | Mexican Health Plan
Assumptions used to determine the pension obligation and seniority premiums as of year-end and the net cost in the ensuing year
Asset allocation (as a percent)	74.00%	73.00%
Post retirement defined benefit plan | Treasury bills | Mexican Health Plan
Assumptions used to determine the pension obligation and seniority premiums as of year-end and the net cost in the ensuing year
Asset allocation (as a percent)	26.00%	27.00%
Post-retirement Health Care Plan | Expatriate Plan
Assumptions used to determine the pension obligation and seniority premiums as of year-end and the net cost in the ensuing year
Discount rate (as a percent)	4.25%	3.35%	3.95%