Earnings Per Share - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share amount	500,000	600,000	500,000	700,000
Additional authorized repurchase amount					$ 93.0
Number of shares repurchased	283,283	166,570	1,074,574	1,353,020
Repurchase of common stock, value	$ 11.4	$ 6.5	$ 43.0	$ 47.5
Treasury stock reissued, shares			225,783	1,014,554