Accounts Receivable Accounts Receivable, Net (Details) $ in Thousands, AUD in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2016 USD ($)	Sep. 30, 2016 AUD	Sep. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable			$ 384,020	$ 388,671
Allowance for doubtful accounts			(17,899)	(6,213)
Accounts receivable, net			366,121	382,458
Accounts receivable - trade [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable			355,289	339,100
Accounts receivable - grants from outside parties [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable			10,750	22,997	$ 25,000
Accounts receivable - insurance and other third-party claims [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable			17,981	$ 26,574
Australian Operations [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for doubtful accounts	$ 8,100
Australian Operations [Member] | Accounts receivable - insurance and other third-party claims [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable			5,100
Arrium Limited [Member] | Australian Operations [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for doubtful accounts		AUD 10.9	$ 8,300