Commitments Contingencies and Other Matters - Additional Information (Detail) (USD $)	6 Months Ended
	Jun. 30, 2014
Commitments and Contingencies Disclosure [Line Items]
Letters of credit, collateral for retrospective premiums and retained losses	$ 39,800,000
Commitments to purchase major equipment	347,000,000
Current obligation	18,300,000
Obligation for remainder of the year	817,000
Non Revolving Senior Secured Term Loan
Commitments and Contingencies Disclosure [Line Items]
Advance to non-affiliates	12,000,000
Notes receivable interest rate	5.00%
Notes receivable	11,800,000
Repayment of notes receivable	5,000,000
Notes receivable outstanding	$ 6,800,000