Long-Term Debt and Notes Payable - Additional Information 2 (Detail) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Debt issuance costs	$ 24.0	$ 27.1
Mexico [Member]
Debt Instrument [Line Items]
Bonds issued related to JRMSA general agreement of indemnity	49.8	52.5
Reimbursement Agreement [Member]
Debt Instrument [Line Items]
Bank guarantees issued	$ 75.6	$ 56.2