Annual report pursuant to Section 13 and 15(d)

Share-Based Compensations - Summary of Stock Option Transactions under Plans (Detail)

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Share-Based Compensations - Summary of Stock Option Transactions under Plans (Detail) (USD $)
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of Shares, Options outstanding at end of period 546,595    
Number of Shares, Options exercisable at end of period 154,970    
Weighted-Average Exercise Price Per Share, Options outstanding at beginning of period $ 37.44 $ 81.27 $ 95.45
Weighted-Average Exercise Price Per Share, Options granted $ 16.43 $ 12.54 $ 9.88
Weighted-Average Exercise Price Per Share, Options exercised $ 11.37 $ 8.32  
Weighted-Average Exercise Price Per Share, Options forfeited $ 12.50 $ 8.61 $ 64.89
Weighted-Average Exercise Price Per Share, Options expired $ 81.20 $ 98.76 $ 39.09
Weighted-Average Exercise Price Per Share, Options outstanding at end of period $ 28.09 $ 37.44 $ 81.27
Weighted-Average Exercise Price Per Share, Options exercisable at end of period $ 59.77 $ 66.19 $ 104.25
Stock Option Awards [Member]
      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of Shares, options outstanding at beginning of period 342,950 143,325 133,361
Number of Shares, Options granted 305,000 221,750 25,000
Number of Shares, Options exercised (46,113) (1,250)  
Number of Shares, Options forfeited (36,566) (5,375) (425)
Number of Shares, Options expired (18,676) (15,500) (14,611)
Number of Shares, Options outstanding at end of period 546,595 342,950 143,325
Number of Shares, Options exercisable at end of period 154,970 159,762 107,475