Reconciliation of Internally Reported Income (Loss) from Operations to Externally Reported Income (Loss) from Operations by Business Segment (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2012
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Environmental remediation expense	$ 12,500	$ 12,500