XML 61 R65.htm IDEA: XBRL DOCUMENT v2.4.0.8
Asset Retirement Obligation - Schedule of Asset Retirement Obligation (Detail) (USD $)
In Thousands, unless otherwise specified
9 Months Ended
Sep. 30, 2014
Sep. 30, 2013
Asset Retirement Obligation Disclosure [Abstract]    
Balance at January 1, $ 5,032 $ 8,882
Accretion 115 234
Payments (767) (2,719)
Gain (128) (1,255)
Balance at September 30, $ 4,252 $ 5,142