Share-Based Compensation (Costs Associated with Share-Based Compensation Plans) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation	$ 7,265	$ 8,404	$ 46,633	$ 44,000
RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation	6,084	7,049	41,908	39,763
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation	$ 1,181	$ 1,355	$ 4,725	$ 4,237