Total Gross Unrecognized Estimated Compensation Expense and Expected Weighted-Average Periods (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized estimated compensation expense, gross amount	$ 33.2
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized estimated compensation expense, gross amount	4.7
Weighted-average period for expense recognition	1 year 9 months 18 days
Restricted stock and restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized estimated compensation expense, gross amount	23.3
Weighted-average period for expense recognition	2 years 1 month 6 days
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized estimated compensation expense, gross amount	$ 5.2
Weighted-average period for expense recognition	1 year 9 months 18 days