Share Based Compensation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended	1 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	May 30, 2013 Two Thousand Ten Equity Compensation Plan [Member]	Sep. 30, 2013 Minimum [Member] Stock Options [Member]	Sep. 30, 2013 Minimum [Member] Restricted Stock [Member]	Sep. 30, 2013 Maximum [Member] Stock Options [Member]	Sep. 30, 2013 Maximum [Member] Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in authorized number of shares of common stock						6,500,000
Shares available for grant under the Plans	7,189,714		7,189,714
Tax benefits recorded on stock based compensation	$ 1.5	$ 1.4	$ 4.2	$ 3.8
Period of vesting provisions (in years)							1 year	1 year	9 years	4 years
Aggregate intrinsic value of options exercisable	$ 261.2		$ 261.2
Weighted average remaining contractual term of options exercisable (in years)			5 years 10 months 24 days
Weighted-average remaining contractual life for options outstanding (in years)			6 years 10 months 24 days		7 years 4 months 24 days