Note 13 - Notes Payable (Detail)	1 Months Ended		12 Months Ended
	Mar. 31, 2008 MXN	Apr. 30, 2007 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2012 MXN	Dec. 31, 2012 Libor [Member] Line of Credit [Member]	Dec. 31, 2012 Libor [Member] Notes Payable, Other Payables [Member]	Dec. 31, 2012 TIIE [Member] Unsecured Debt [Member]	Dec. 31, 2012 Line of Credit [Member]	Jan. 31, 2013 Senior Notes [Member] USD ($)	Dec. 31, 2012 Senior Notes [Member]	Dec. 31, 2012 Unsecured Debt [Member] USD ($)	Dec. 31, 2012 Letters of Credit [Member] USD ($)
Debt Instrument, Basis Spread on Variable Rate (in Basis Points)							1.05%	3.50%	1.35%				1.05%
Debt Instrument, Face Amount											$ 100,000,000
Debt Instrument, Interest Rate, Stated Percentage	8.58%										6.125%	6.00%
Proceeds from Issuance of Senior Long-term Debt		300,000,000
Debt Covenants, Dividend Payment Restriction, Maximum Payment		26,000,000
Line of Credit Facility, Maximum Borrowing Capacity			1,750,000,000
Debt Instrument, Additional Options, Term										1 year
Line of Credit Facility, Commitment Fee Percentage			0.20%
Line of Credit Facility, Competitive Bid Option			875,000,000
Line of Credit Facility, Sub Limit			500,000,000
Line of Credit Facility, Amount Outstanding			249,900,000											27,300,000
Unsecured Debt			76,900,000			1,000,000,000							400,000,000
Number of Additional One-Year Options			3
Option Term													1 year
Proceeds from Issuance of Medium-term Notes (in Pesos)	1,000,000,000
Repayments of Unsecured Debt (in Pesos)	500,000,000		215,900,000	92,600,000	471,725,000
Extension Term													5 years
Debt, Weighted Average Interest Rate													4.72%
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months													555.4
Long-term Debt, Maturities, Repayments of Principal in Year Two													694.8
Long-term Debt, Maturities, Repayments of Principal in Year Three													600.0
Long-term Debt, Maturities, Repayments of Principal in Year Four													300.0
Long-term Debt, Maturities, Repayments of Principal in Year Five													290.9
Long-term Debt, Maturities, Repayments of Principal after Year Five													$ 751.0