Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation - Summary of Stock Options Outstanding under Plans (Detail)

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Share-Based Compensation - Summary of Stock Options Outstanding under Plans (Detail) (USD $)
In Thousands, except Share data, unless otherwise specified
 3 Months Ended 9 Months Ended
Sep. 30, 2014
Y
Sep. 30, 2013
Sep. 30, 2014
Y
Sep. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]        
Options outstanding at beginning of period 581,913   546,595  
Number of Shares, Options granted 28,000   133,000  
Number of Shares, Options exercised (687) (38,437) (34,382) (40,678)
Number of Shares, Options forfeited (1,876)   (9,751)  
Number of Shares, Options expired (2,875)   (30,987)  
Number of Shares, Options outstanding at end of period 604,475   604,475  
Number of Shares, Options exercisable at end of period 194,757   194,757  
Weighted-Average Exercise Price Per Share, Options outstanding at beginning of period $ 24.32   $ 28.09  
Weighted-Average Exercise Price Per Share, Options granted $ 20.57   $ 21.60  
Weighted-Average Exercise Price Per Share, Options exercised $ 12.54   $ 12.54  
Weighted-Average Exercise Price Per Share, Options forfeited $ 12.54   $ 12.54  
Weighted-Average Exercise Price Per Share, Options expired $ 109.71   $ 106.26  
Weighted-Average Exercise Price Per Share, Options outstanding at end of period $ 23.79   $ 23.79  
Weighted-Average Exercise Price Per Share, Options exercisable at end of period $ 37.21   $ 37.21  
Weighted-Average Remaining Contractual Life, Options outstanding at beginning of period 8.6   8.4  
Weighted-Average Remaining Contractual Life, Options granted 10 years   9 years 8 months 12 days  
Weighted-Average Remaining Contractual Life, Options exercised 8.2   7.9  
Weighted-Average Remaining Contractual Life, Options forfeited 8 years 2 months 12 days   8 years 2 months 12 days  
Weighted-Average Remaining Contractual Life, Options expired 3 years 3 months 18 days   6 months  
Weighted-Average Remaining Contractual Life, Options outstanding at end of period 8.5   8.5  
Weighted-Average Remaining Contractual Life, Options exercisable at end of period 7 years 2 months 12 days   7 years 2 months 12 days  
Aggregate Intrinsic Value of In-the-Money Options, Options outstanding at beginning of period $ 2,168   $ 3,384  
Aggregate Intrinsic Value of In-the-Money Options, Options exercised          
Aggregate Intrinsic Value of In-the-Money Options, Options forfeited          
Aggregate Intrinsic Value of In-the-Money Options, Options expired          
Aggregate Intrinsic Value of In-the-Money Options, Options outstanding at end of period 2,188   2,188  
Aggregate Intrinsic Value of In-the-Money Options, Options exercisable at end of period 871   871  
Aggregate Intrinsic Value of In-the-Money Options, Options granted