Debt - Amended Credit Agreement (Details)	Mar. 23, 2017 USD ($)	Sep. 30, 2017 AUD	Sep. 30, 2017 USD ($)	Mar. 23, 2017 AUD	Mar. 23, 2017 USD ($)	Mar. 22, 2017 AUD	Mar. 22, 2017 USD ($)	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
Loan costs			$ 7,961,000					$ 0
Term loan			796,000,000					289,500,000
Revolver			$ 245,874,000					$ 515,000,000
Weighted average interest rate		3.50%	3.50%
Revolver
Debt Instrument [Line Items]
Revolver			$ 246,000,000
Additional Revolver
Debt Instrument [Line Items]
Borrowing capacity increase			589,000,000
Revolving Credit Facility | Line of Credit | Amended Credit Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity					$ 900,000,000
Leverage ratio				2.50	2.50
Total leverage ratio, maximum				6.25	6.25
Senior secured leverage ratio				3.50	3.50
Interest coverage ratio				3.00	3.00
Revolving Credit Facility | Line of Credit | Amended Credit Agreement | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate				2.25%	2.25%
Letter of Credit
Debt Instrument [Line Items]
Long-term debt			65,000,000
Letter of Credit | Line of Credit | Amended Credit Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity | AUD				AUD 275,000,000		AUD 225,000,000
Loan costs					$ 7,000,000
Letter of Credit | Line of Credit | Bank Guarantee and Standby Sub Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		AUD 100,000,000	78,300,000.0
Accordion | Line of Credit | Amended Credit Agreement
Debt Instrument [Line Items]
Accordion feature, increase limit	$ 450,000,000
Term Loan
Debt Instrument [Line Items]
Term loan			$ 796,000,000
Term Loan | Line of Credit | Amended Credit Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity					$ 800,000,000		$ 291,000,000
Term Loan | Line of Credit | Amended Credit Agreement | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate				2.25%	2.25%
Interest rate				0.75%	0.75%