Long-term Debt Schedule of Future Payments Including Capital Leases (Details) $ in Thousands, AUD in Millions	12 Months Ended
	Dec. 31, 2017 AUD	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 01, 2010 AUD	Dec. 01, 2010 USD ($)
Debt Instrument, Redemption [Line Items]
2018		$ 36,866
2019		39,849
2020		1,586,249
2021		471,666
2022		12,380
Thereafter		246,112
Total		2,393,122
Non-interest bearing loan, carrying value		2,256,312	$ 2,273,058
Non interest bearing note [Member]
Debt Instrument, Redemption [Line Items]
Non-interest bearing loan		39,100		AUD 50.0	$ 48,200
Non-interest bearing loan, maturity date	Jan. 14, 2054
Non-interest bearing loan, carrying value	AUD 3.1	$ 2,400		AUD 1.8	$ 1,700