Receivables - Receivables (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 31,963		$ 39,278
Oil and Gas Joint Interest Billing Receivables	5,410		3,896
Allowance for bad debts	(26)		(26)
Receivables, net	31,937		39,252
Loan secured by real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	6,172		7,610
Notes receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	7,892		7,987
Average interest rate	4.42%	5.00%
Oil and gas revenue accrual receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	7,544		8,137
Receivables and accrued interest [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 4,945		$ 11,648