Stock-Based Compensation - Additional Information (Detail) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($) shares
Performance-Based Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock units awarded | shares	1.3
Aggregate grant date fair value | $	$ 64.8
Time-Based RSU's [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock units awarded | shares	0.4
Aggregate grant date fair value | $	$ 17.5