Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Name:	us-gaap_GoodwillImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Goodwill and Other Intangible Assets - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013 Reporting_Unit	Sep. 30, 2013	Dec. 31, 2012
Goodwill [Line Items]
Goodwill			$ 89.9	$ 97.0
Number of reportable units tested for goodwill impairment at interim period		1
Impairment charges in the second quarter	6.8
Reporting Unit Tested for Interim Goodwill Impairment [Member]
Goodwill [Line Items]
Goodwill			$ 0