XML 70 R54.htm IDEA: XBRL DOCUMENT v3.4.0.3
Asset Retirement Obligation - Schedule of Asset Retirement Obligation (Detail) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]    
Balance at January 1, $ 419 $ 4,114
Accretion 0 29
Payments 0 (419)
Gain 0 (107)
Balance at March 31, $ 419 $ 3,617