Net Income (Loss) Attributable to Noncontrolling Interests - Additional Information (Detail)	Sep. 30, 2014 International Finance Corporation [Member]	Sep. 30, 2014 Minera Yanacocha [Member]	Sep. 30, 2014 Compania de Minas Buenaventura SAA [Member]	Sep. 30, 2014 Batu Hijau [Member]	Apr. 30, 2014 TMAC [Member] Minimum [Member]	Apr. 30, 2014 TMAC [Member] Maximum [Member]
Noncontrolling Interest [Line Items]
Ownership/Economic interest in subsidiaries		51.35%		48.50%	45.20%	70.40%
Noncontrolling interest, ownership percentage by noncontrolling owners	5.00%		43.65%