Pension Plan - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Amount of contributions to contributory plan	$ 29.9	$ 27.3	$ 21.7
Accumulated benefit obligation	102.3	112.7
Fair value of plan assets exceeded accumulated benefit obligation	4.1	8.6
Estimated net loss that will be amortized from accumulated other comprehensive income over the next fiscal year	$ 1.1