Share-Based Compensation Plans - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended		0 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 CompensationPlan	Jun. 30, 2013	Mar. 31, 2014 Performance Restricted Stock Units	Mar. 31, 2013 Performance Restricted Stock Units	Apr. 16, 2014 2012 Long Term Incentive Plan	Jun. 30, 2014 2012 Long Term Incentive Plan	Jun. 30, 2014 Directors Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional shares authorized							2,900,000
Number of remaining shares that may be issued								6,510,679	35,707
Number of employee stock purchase programs			2
Share-based payment arrangements	$ 17,200,000	$ 12,700,000	$ 36,700,000	$ 28,500,000
Award requisite service periods					3 years	3 years
Fair value assumptions, risk-free interest rate					0.70%	0.42%
Fair value assumptions, dividend yield					0.62%	0.81%
Fair value assumptions, expected life in years					2 years 10 months 17 days	2 years 10 months 17 days
Unrecognized compensation expenses related to share-based payment arrangements	$ 91,900,000		$ 91,900,000
Weighted-average period of recognizing unrecognized compensation expenses related to share-based compensation, in years			3 years