Annual report pursuant to Section 13 and 15(d)

Share-Based Compensations - Summary of Transactions for Non-Vested Stock Options (Detail)

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Share-Based Compensations - Summary of Transactions for Non-Vested Stock Options (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    
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 vested $ 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 outstanding at end of period $ 28.09 $ 37.44 $ 81.27
Non-vested stock options [Member]
      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of Shares, options outstanding at beginning of period 183,188 35,850 33,775
Number of Shares, Options granted 305,000 221,750 25,000
Number of Shares, Options vested (59,997) (69,037) (22,500)
Number of Shares, Options forfeited (36,566) (5,375) (425)
Number of Shares, Options outstanding at end of period 391,625 183,188 35,850
Weighted-Average Exercise Price Per Share, Options outstanding at beginning of period $ 12.37 $ 25.20 $ 17.68
Weighted-Average Exercise Price Per Share, Options granted $ 16.43 $ 12.54 $ 9.88
Weighted-Average Exercise Price Per Share, Options vested $ 12.14 $ 13.20 $ 56.54
Weighted-Average Exercise Price Per Share, Options forfeited $ 12.50 $ 8.61 $ 64.89
Weighted-Average Exercise Price Per Share, Options outstanding at end of period $ 15.56 $ 12.37 $ 25.20