Stock-based Compensation - Schedule of Weighted Average Grant Date Fair Value Per Share of Performance-Based RSUs and Assumptions Used to Estimate Fair Value (Detail) - Performance-based RSUs [Member] - $ / shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Short Term [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value per share	$ 39.47	$ 37.00
Service period (years)	1 year	1 year
Long Term [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value per share	$ 36.78	$ 38.64
Service period (years)	3 years	2 years