Commitments & Contingencies - Additional Information (Detail) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Loss Contingencies [Line Items]
Accrued Insurance Liabilities	$ 9,211,000	$ 9,715,000
Baker Energy [Member]
Loss Contingencies [Line Items]
Accrued Insurance Liabilities	2,400,000	2,700,000
Corresponding receivables	1,500,000	1,700,000
Reliance Group [Member]
Loss Contingencies [Line Items]
Amount recoverable under Insurance policy with Reliance	2,500,000
Distribution from Reliance related to claims received	1,100,000
Related receivables recorded from Reliance	$ 0	$ 0