Share-Based Compensation (Summary of Stock Option Activity) (Detail)
$ / shares in Units, shares in Thousands, $ in Thousands
 6 Months Ended
Jun. 30, 2016
USD ($)
$ / shares
shares
Stock option  
Balance at December 31, 2015 | shares 132
Balance at June 30, 2016 | shares 132
Vested and expected to vest at June 30, 2016 | shares 132
Exercisable at June 30, 2016 | shares 66
Stock option, weighted-average exercise price  
Beginning Balance, Weighted-average exercise price | $ / shares $ 27.66
Ending Balance, Weighted-average exercise price | $ / shares 27.66
Vested and expected to vest at June 30, 2016, Weighted-average exercise price | $ / shares 27.66
Exercisable at June 30, 2016, Weighted-average exercise price | $ / shares $ 27.66
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures  
Ending Balance, Weighted-average remaining contractual term, years 7 years 6 months
Vested and expected to vest at June 30, 2016, Weighted-average remaining contractual term, years 7 years 6 months
Exercisable at June 30, 2016, Weighted-average remaining contractual term, years 7 years 6 months
Ending Balance, Aggregate intrinsic value | $ $ 1,662
Vested and expected to vest at March 31, 2016, Aggregate intrinsic value | $ 1,662
Exercisable at March 31, 2016, Aggregate intrinsic value | $ $ 831