Note 12 - Notes Payable (Details) - Notes Payable (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Debt Instrument [Line Items]
Balance (in Dollars)	$ 3,192,167		$ 3,186,047
Interest Rate Range (Low)	3.62%
Interest Rate Range (High)	4.97%
Senior Notes [Member]
Debt Instrument [Line Items]
Balance (in Dollars)	1,540,900		1,140,900
Interest Rate Range (Low)	3.13%		3.13%
Interest Rate Range (High)	6.88%		6.88%
Medium-term Notes [Member]
Debt Instrument [Line Items]
Balance (in Dollars)	850,000		1,044,600
Interest Rate Range (Low)	4.30%		4.30%
Interest Rate Range (High)	5.78%		5.78%
Unsecured Debt [Member]
Debt Instrument [Line Items]
Balance (in Dollars)	400,000	[1]	400,000	[2]
Interest Rate Range (Low)		[1],[3]		[2],[3]
Interest Rate Range (High)		[1],[3]		[2],[3]
Canadian Notes Payable [Member]
Debt Instrument [Line Items]
Balance (in Dollars)	301,300		329,500
Interest Rate Range (Low)	3.86%		3.86%
Interest Rate Range (High)	5.99%		5.99%
Line of Credit [Member]
Debt Instrument [Line Items]
Balance (in Dollars)	100,000		194,500
Interest Rate Range (Low)		[4]		[3]
Interest Rate Range (High)		[4]		[3]
Mexican Term Loan [Member]
Debt Instrument [Line Items]
Balance (in Dollars)			$ 76,500
Interest Rate Range (Low)				[5]
Interest Rate Range (High)				[5]

[1] During January 2014, the Company exercised its one-year extension option to extend the maturity date to April 2015.

[2] During January 2015, the Company repaid its $400.0 million term loan which was scheduled to mature in 2015 with a new $650.0 million unsecured term loan that bears interest at a rate equal to LIBOR + .95% and is scheduled to mature in 2017, with three one-year extensions at the Company's discretion.

[3] Interest rate is equal to LIBOR + 1.05% (1.21% and 1.22% at December 31, 2014 and 2013, respectively).

[4] Interest rate is equal to LIBOR + .925% (1.09% at December 31, 2014).

[5] Interest rate is equal to TIIE (Equilibrium Interbank Interest Rate) plus 1.35% (5.15% at December 31, 2013).