v2.4.0.8
Summary of Performance Based Restricted Stock Units (Detail) (USD $)
In Thousands, except Share data, unless otherwise specified
 9 Months Ended
Sep. 30, 2014
Dec. 31, 2013
Sep. 30, 2013
Dec. 31, 2012
Performance-based units outstanding, Number of Units 2,156,312 [1]      
Performance-based units vested and deferred, Number of Units 545,500 [2]      
Performance-based units outstanding, Weighted Average Remaining Contractual Life (Years) 1 year 2 months 9 days [1]      
Performance-based units outstanding, Aggregate Intrinsic Value $ 8,410 [1]      
Performance-based units vested and expected to vest, Aggregate Intrinsic Value 5,987 [3]      
Performance-based units vested and deferred, Aggregate Intrinsic Value 2,127 [2]      
Performance Stock Units
        
Performance-based units outstanding, Number of Units 604,630 [1] 279,630 360,000 235,000
Performance-based units vested and expected to vest, Number of Units 581,138 [4]      
Performance-based units vested and deferred, Number of Units 37,130 [2]      
Performance-based units outstanding, Weighted Average Remaining Contractual Life (Years) 1 year 4 months 24 days [1]      
Performance-based units vested and expected to vest, Weighted Average Remaining Contractual Life (Years) 1 year 4 months 13 days [4]      
Performance-based units outstanding, Aggregate Intrinsic Value 2,358 [1]      
Performance-based units vested and expected to vest, Aggregate Intrinsic Value 2,122 [4]      
Performance-based units vested and deferred, Aggregate Intrinsic Value $ 145 [2]      
[1] Total outstanding units include all unvested and vested but deferred shares which will be released to the employee upon separation from service.
[2] Vested awards with deferral elections to be released to the employee upon separation from service.
[3] Includes shares vested to-date and expected to vest shares which comprises of unvested shares net of expected forfeitures.
[4] Includes shares vested to-date and expected to vest shares which is comprised of unvested shares net of expected forfeitures.