Debt (Credit Agreement) (Details)	12 Months Ended						12 Months Ended				0 Months Ended		0 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2014 Revolver USD ($)	Dec. 31, 2014 Term Loan USD ($)	Dec. 31, 2014 Letter of credit USD ($)	Dec. 31, 2013 Amended and Restated Credit Agreement USD ($)	Dec. 31, 2014 Additional Revolver USD ($)	Dec. 31, 2014 Australian LC Facility Letter of credit AUD	Aug. 27, 2014 Australian LC Facility Letter of credit AUD	Aug. 27, 2014 Revolver LIBOR	Aug. 27, 2014 Revolver Revolving Credit Facility USD ($)	Aug. 27, 2014 Term Loan LIBOR	Aug. 27, 2014 Term Loan LIBOR Minimum	Aug. 27, 2014 Credit Facility USD ($)	Aug. 27, 2014 Credit Facility USD ($)	Aug. 27, 2014 Credit Agreement	Aug. 27, 2014 Credit Facility Term Loan Term Loan USD ($)
Debt Instrument [Line Items]
Debt instrument, face amount																		$ 296,300,000
Maximum borrowing capacity										225,000,000		700,000,000
Debt instrument basis spread on variable rate											2.25%		2.50%	0.75%
Write off amount of deferred financing fees															400,000
Capitalized loan costs	53,900,000	33,100,000														4,600,000
Total leverage ratio																	5.75
Senior secured leverage ratio																	3.50
Interest coverage ratio																	3.00
Term Loans	295,500,000	298,500,000			295,500,000
Line of Credit, amount outstanding	70,000,000	340,000,000		70,000,000
Outstanding balance	1,625,958,000					62,000,000			214,000,000
Borrowing capacity remaining								568,000,000
Weighted average interest rates on outstanding borrowings	3.20%
Loss on extinguishment of debt	$ 0	$ 20,657,000	$ 8,462,000				$ 5,500,000