Commitments and Contingencies (Details 2) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended	12 Months Ended			48 Months Ended			3 Months Ended
	Jan. 31, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2017 USD ($)	Mar. 18, 2014 USD ($)	Dec. 31, 2013 USD ($)	Mar. 31, 2014 Prarie State Energy Campus [Member] mW	Mar. 31, 2014 Monto Coal Pty Limited [Member] AUD	Mar. 31, 2014 Oklahoma Lead Litigation [Member] USD ($) sites	Dec. 31, 2013 Oklahoma Lead Litigation [Member] USD ($)
Loss Contingency [Abstract]
Ownership Percentage In Subsidiaries										51.00%
Damages sought										1,193.2
Class B shareholders claim for unpaid dividends		29.0
Interest on Class B shareholders claim for unpaid dividends		5.6
Requisite security filed with the court		48.4
Damages awarded by the arbitrator to Eagle on some of Eagle's claims							23.4
Estimated loss associated with Eagle Mining arbitration								7.8
Additional charge recorded as a result of the damages awarded to Eagle in arbitration		15.6
Number of national priority list sites based on the Superfund Amendments and Reauthorization Act of 1986 at which Gold Fields or the former affiliate, has been named a potentially responsible party (PRP)											5
Number of additional national priority list sites in which CERCLA claims were asserted											13
Total number of national priority list sites											18
Reduced number of national priority list sites due to completion of work, transfer or regulatory inactivity											8
Undiscounted environmental clean-up liabilities, total											62.5	63.8
Undiscounted environmental clean-up liabilities, current											17.0	18.3
Funding of the newly established VEBA						310.0
Initial Payment based on the construct of the negotiated settlement	90.0
Payment to Patriot based on the construct of the negotiated settlement	70.0
Payment to the VEBA based on the construct of the negotiated settlement	$ 20.0		$ 70.0	$ 75.0	$ 75.0
Capacity of new electricity generation project									1,600
Undivided interest percent of new electricity generation project									5.06%