Share-Based Compensation (Summary of Stock Option Activity) (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($) $ / shares shares
Stock option, number outstanding
Beginning Balance, Number outstanding	686
Exercised, Number outstanding	(307)
Ending Balance, Number outstanding	379
Vested and expected to vest at September 30, 2015, Number outstanding	379
Exercisable at September 30, 2015, Number outstanding	279
Stock option, weighted-average exercise price
Beginning Balance, Weighted-average exercise price | $ / shares	$ 20.18
Exercised, Weighted-average exercise price | $ / shares	16.79
Ending Balance, Weighted-average exercise price | $ / shares	22.94
Vested and expected to vest at September 30, 2015, Weighted-average exercise price | $ / shares	22.94
Exercisable at September 30, 2015, Weighted-average exercise price | $ / shares	$ 21.26
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures
Ending Balance, Weighted-average remaining contractual term, years	3 years
Vested and expected to vest at September 30, 2015, Weighted-average remaining contractual term, years	3 years
Exercisable at September 30, 2015, Weighted-average remaining contractual term, years	1 year 1 month 6 days
Ending Balance, Aggregate intrinsic value | $	$ 6,107
Vested and expected to vest at September 30, 2015, Aggregate intrinsic value | $	6,107
Exercisable at September 30, 2015, Aggregate intrinsic value | $	$ 4,974