Note 9 - Notes Payable (Details)	3 Months Ended	9 Months Ended							1 Months Ended				9 Months Ended
	Mar. 31, 2014	Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($)	Sep. 30, 2014 5.95% Senior Notes [Member] Unsecured Debt [Member] USD ($)	Sep. 30, 2014 4.82% Senior Notes [Member] Unsecured Debt [Member] USD ($)	Sep. 30, 2014 Term Loan [Member] Equilibrium Interbank Interest Rate [Member]	Sep. 30, 2014 Term Loan [Member] USD ($)	Sep. 30, 2014 Term Loan [Member] MXN	Apr. 30, 2014 Unsecured Debt [Member] USD ($)	Mar. 31, 2014 Previous Credit Facility [Member] USD ($)	Mar. 31, 2014 Including Accordion Feature [Member] USD ($)	Sep. 30, 2014 Letter of Credit [Member] USD ($)	Sep. 30, 2014 London Interbank Offered Rate (LIBOR) [Member]
Note 9 - Notes Payable (Details) [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 1,750,000,000								$ 1,750,000,000	$ 2,250,000,000
Number of Options to Extend Maturity of Credit Facility		2
Line of Credit Facility, Length of Extension for Each Option	6 months
Debt Instrument, Basis Spread on Variable Rate						1.35%							0.925%
Line of Credit Facility, Sub Limit		500,000,000
Long-term Line of Credit		250,000,000										1,100,000
Debt Instrument, Face Amount								1,000,000,000	500,000,000
Debt Instrument, Term									7 years
Debt Instrument, Interest Rate, Stated Percentage				5.95%	4.82%				3.20%
Proceeds from Issuance of Senior Long-term Debt									495,400,000
Repayments of Unsecured Debt		370,842,000	446,717,000	100,000,000	194,600,000
Repayments of Long-term Debt							$ 76,300,000	1,000,000,000