Share-Based Compensation Plans - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	1 Months Ended			1 Months Ended		3 Months Ended
	Sep. 30, 2013 CompensationPlan	Apr. 17, 2013 2012 Long Term Incentive Plan	Sep. 30, 2013 2012 Long Term Incentive Plan	Sep. 30, 2013 Directors Plan	Jul. 31, 2013 Management Stock Purchase Program	Jul. 31, 2012 Management Stock Purchase Program	Mar. 31, 2013 Performance Restricted Stock Units	Mar. 31, 2012 Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional shares authorized		2,000,000
Number of remaining shares that may be issued			5,710,855	39,843
Number of employee stock purchase programs	2
Awards requisite service period							3 years
Fair value assumptions, risk-free interest rate					0.10%	0.16%	0.42%	0.41%
Fair value assumptions, dividend yield					0.80%	0.90%	0.81%	0.85%
Fair value assumptions, expected life in years					7 months 6 days	7 months 6 days	2 years 10 months 17 days	2 years 9 months 29 days
Number of shares granted in period					200,000	200,000
Fair value per share of shares granted in period					$ 37.20	$ 38.33
Fair value assumptions, expected volatility					15.00%	20.00%
Unrecognized compensation expenses related to share-based payment arrangements	$ 79.3
Weighted-average period of recognizing unrecognized compensation expenses related to share-based compensation, in years	2 years