XML 17 R55.htm IDEA: XBRL DOCUMENT v2.4.0.6
Fair Value of Financial Instruments - Additional Information (Detail) (USD $)
6 Months Ended
Jun. 30, 2012
Dec. 31, 2011
Financial Instruments [Line Items]    
Available-for-sale Securities, Gross Realized Gain (Loss) $ 1,557,000  
Estimated fair value of total debt $ 371,700,000 $ 76,800,000