Annual report pursuant to Section 13 and 15(d)

Supplemental Information on Oil and Gas Producing Activities - Capitalized Costs Relating to Oil and Gas Producing Activities (Detail)

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Supplemental Information on Oil and Gas Producing Activities - Capitalized Costs Relating to Oil and Gas Producing Activities (Detail) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Capitalized Costs Relating to Oil and Gas Producing Activities:      
Properties not being amortized $ 88,194 $ 66,794 $ 46,047
Properties being amortized 222,032 [1] 195,329 [1] 182,820 [1]
Total capitalized costs 310,226 262,123 228,867
Less accumulated depreciation, depletion, and amortization (171,854) (155,681) (129,166)
Net capitalized costs $ 138,372 $ 106,442 $ 99,701
[1] Includes $5.2 million, $4.7 million, and $10.4 million asset retirement cost in 2013, 2012, and 2011, respectively.