Fair Value Measurement - Additional Information (Detail) (Assets measured on a nonrecurring basis, USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Assets measured on a nonrecurring basis
Assets Measured On Nonrecurring Basis [Line Items]
Fair values reduced by estimated costs to sell	$ 0.9	$ 0.4	$ 0.9	$ 0.4