Debt Revolving Credit and Term Loan Agreements (Details)	12 Months Ended					12 Months Ended														12 Months Ended
	Dec. 31, 2013 USD ($)	Dec. 31, 2013 AUD	Dec. 31, 2012	Dec. 31, 2013 Revolving Credit Facility [Member] USD ($)	Dec. 31, 2012 Revolving Credit Facility [Member] USD ($)	Dec. 31, 2013 Medium-term Notes [Member] USD ($)	Dec. 31, 2012 Medium-term Notes [Member] USD ($)	Nov. 20, 2012 Medium-term Notes [Member] USD ($)	Sep. 20, 2010 Medium-term Notes [Member] USD ($)	Dec. 31, 2013 JPMorgan Chase Bank NA as Administrative Agent Bank of America NA and RBS Citizens NA as Co-Syndication Agents [Member] Revolving Credit Facility [Member] USD ($)	Nov. 20, 2012 JPMorgan Chase Bank NA as Administrative Agent Bank of America NA and RBS Citizens NA as Co-Syndication Agents [Member] Revolving Credit Facility [Member] USD ($)	Dec. 31, 2013 JPMorgan Chase Bank NA as Administrative Agent Bank of America NA and RBS Citizens NA as Co-Syndication Agents [Member] Line of Credit [Member] USD ($)	Dec. 31, 2012 Co-lead Arrangers Bank of America Securities LLC, JP Morgan Securities LLC, and RBS Citizens N.A. and a Syndicate of Lenders [Member] Revolving Credit Facility [Member] USD ($)	Sep. 20, 2010 Co-lead Arrangers Bank of America Securities LLC, JP Morgan Securities LLC, and RBS Citizens N.A. and a Syndicate of Lenders [Member] Revolving Credit Facility [Member] USD ($)	Dec. 31, 2012 Co-lead Arrangers Bank of America Securities LLC, JP Morgan Securities LLC, and RBS Citizens N.A. and a Syndicate of Lenders [Member] Line of Credit [Member] USD ($)	Dec. 31, 2013 Collateral Member One [Member] Line of Credit [Member]	Dec. 31, 2013 Collateral Member Two [Member] Line of Credit [Member]	Dec. 31, 2013 NEW ZEALAND JPMorgan Chase Bank NA as Administrative Agent Bank of America NA and RBS Citizens NA as Co-Syndication Agents [Member] Line of Credit [Member] USD ($)	Dec. 31, 2012 Commonwealth of Australia [Member] Co-lead Arrangers Bank of America Securities LLC, JP Morgan Securities LLC, and RBS Citizens N.A. and a Syndicate of Lenders [Member] Line of Credit [Member] USD ($)	Dec. 31, 2013 Minimum [Member] Revolving Credit Facility [Member]	Dec. 31, 2013 Minimum [Member] Line of Credit [Member]	Dec. 31, 2013 Maximum [Member] Revolving Credit Facility [Member]	Dec. 31, 2013 Maximum [Member] Line of Credit [Member]
Debt Instrument
Line of Credit Facility, Maximum Borrowing Capacity											$ 400,000,000			$ 275,000,000
Line of Credit Facility, Amount Outstanding								100,000,000	42,500,000				54,300,000
Debt Instrument, Periodic Payment, Principal						2,500,000
Debt Instrument, Final Periodic Payment, Principal						55,000,000
Line of Credit Increase in Maximum Borrowing Capacity Due to Accordian Feature										100,000,000
Equity Interest In Certain Foreign Subsidiaries																66.00%
Equity Interest In Domestic Subsidiaries																	100.00%
Long-term Debt, Gross				77,562,000	54,325,000	90,000,000	100,000,000			77,562,000
Line of Credit Facility, Remaining Borrowing Capacity										285,600,000			331,100,000
Line of Credit Facility, Current Borrowing Capacity	217,600,000
Letters of Credit Outstanding, Amount												36,800,000			14,600,000			30,300,000	6,700,000
Guaranteed Minimum Payments to Australia		6,400,000
Debt Instrument, Interest Rate at Period End	1.72%	1.72%	1.75%
Line of Credit Facility, Commitment Fee Percentage																				0.20%	1.25%	0.325%	2.125%
Consolidated Senior Secured Indebtedness to Consolidated EBITDA, Ratio	3.50	3.50
Consolidated Total Indebtedness to Consolidated EBITDA, Ratio	4.00	4.00
Portion of Rent Expense Under Capital Leases That is Treated as Interest Expense, Ratio	4.00	4.00
Debt Instrument, Basis Points	1.00	1.00