Note 7 - Debt (Details)	1 Months Ended		3 Months Ended		6 Months Ended				0 Months Ended	6 Months Ended	1 Months Ended	6 Months Ended
	Jul. 31, 2012 USD ($)	May 17, 2012 USD ($)	Jun. 30, 2013 USD ($)	Jun. 30, 2012 USD ($)	Jun. 30, 2013 USD ($)	Jun. 30, 2012 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 21, 2012 5 1/8% Senior Notes [Member] USD ($)	Jun. 30, 2013 5 1/8% Senior Notes [Member]	Jun. 30, 2011 6 1/2% Senior Notes [Member] USD ($)	Jun. 30, 2013 6 1/2% Senior Notes [Member]	Jun. 15, 2005 2 3/8% Senior Subordinated Notes [Member]	Jun. 30, 2013 Australian Credit Facility [Member] AUD
Note 7 - Debt (Details) [Line Items]
Debt Instrument, Face Amount		$ 174,990,000							$ 400,000,000		$ 600,000,000
Redemption of Senior Unsecured Notes Condition One										At any time prior to January15, 2016, the Company may redeem up to 35% of the 5 1/8% Notes at a redemption price of 105.125% of the principal amount, plus accrued and unpaid interest to the redemption date, with the proceeds of certain equity offerings.		At any time prior to June1, 2014, the Company may redeem up to 35% of the 6 1/2% Notes at a redemption price of 106.5% of the principal amount, plus accrued and unpaid interest to the redemption date, with the proceeds of certain equity offerings.
Redemption of Senior Unsecured Notes Condition Two										Prior to January15, 2018, the Company may redeem some or all of the 5 1/8% Notes for cash at a redemption price equal to 100% of their principal amount plus an applicable make-whole premium and accrued and unpaid interest to the redemption date.		Prior to June1, 2014, the Company may redeem some or all of the 6 1/2% Notes for cash at a redemption price equal to 100% of their principal amount plus an applicable make-whole premium and accrued and unpaid interest to the redemption date. On and after June1, 2014, the Company may redeem some or all of the 6 1/2% Notes at redemption prices (expressed as percentages of principal amount), plus accrued and unpaid interest to the redemption date.
Proceeds Of Senior Unsecured Notes Utilized To Repay Its Senior Secured Credit Facilities									334,000,000		515,000,000
Proceeds Of Senior Unsecured Notes Utilized For General Corporate Purposes									61,000,000		75,000,000
Redemption Price as Percentage of Principal Amount Plus Accrued and Unpaid Interest		100.00%
Debt Conversion, Converted Instrument, Shares Issued (in Shares)	3,012,380
Stock Issued During Period, Value, Conversion of Convertible Securities	220,600,000
Debt Instrument, Interest Rate, Effective Percentage													7.17%
Cash and Cash Equivalents, at Carrying Value			225,857,000	114,391,000	225,857,000	114,391,000	253,172,000	71,721,000
Credit Facility Remaining Borrowing Capacity			713,000,000		713,000,000
Line of Credit Facility, Remaining Borrowing Capacity (in Dollars)														300,000,000
Letters of Credit Outstanding, Amount			37,000,000		37,000,000
Interest Costs Capitalized			$ 200,000	$ 1,200,000	$ 500,000	$ 2,500,000