Debt (Details 1)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2012 USD [Member] USD ($)	Dec. 20, 2012 USD [Member] USD ($)	Dec. 31, 2011 USD [Member] USD ($)	Dec. 31, 2012 AUD [Member] USD ($)	Dec. 31, 2011 AUD [Member] USD ($)	Sep. 07, 2011 AUD [Member] AUD
Debt Instrument [Line Items]
7.25% unsecured notes due February 1, 2019	$ 397,479,000	$ 397,065,000
Revolving credit borrowing			240,121,000	240,000,000	0	51,915,000	51,012,000	50,000,000
Commercial paper borrowings	0	109,671,000
Other indebtedness	7,196,000	7,464,000
Total Debt	696,711,000	565,212,000
Less: current portion	(243,327,000)	(112,983,000)
Total Long-Term Debt	$ 453,384,000	$ 452,229,000
Interest rate of debt instrument				1.5107%