Fair Value of Financial Instruments Financial Instruments Carried at Historical Costs (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	$ 2,308,053	$ 2,273,058
Revolving credit facility [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	222,093	74,297
Other debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	2,900	4,882
Credit agreement [Member] | United States term loan [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	1,253,776	1,415,873
Credit agreement [Member] | U.K. term loan [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	124,859	121,149
Australian Credit Agreement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	517,696	484,703
Australian Partner Loan Agreement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	186,729	172,154
Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	2,339,386	2,303,531
Fair Value, Inputs, Level 2 [Member] | Revolving credit facility [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	227,103	81,192
Fair Value, Inputs, Level 2 [Member] | Other debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	2,918	4,889
Fair Value, Inputs, Level 2 [Member] | Credit agreement [Member] | United States term loan [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	1,259,935	1,422,512
Fair Value, Inputs, Level 2 [Member] | Credit agreement [Member] | U.K. term loan [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	127,114	121,594
Fair Value, Inputs, Level 2 [Member] | Australian Credit Agreement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	534,317	501,909
Fair Value, Inputs, Level 2 [Member] | Australian Partner Loan Agreement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 187,999	$ 171,435