Mergers and Acquisitions - After-tax Transaction and Integration Charges Recognized Upon Closing of Acquisition and Included Consolidated Statements of Operations (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Business Acquisition [Line Items]
Total accounting charges	$ 15.4
NMGI [Member]
Business Acquisition [Line Items]
Legal and other consultants	0.1	$ 5.3	$ 0.4	$ 7.2
Bridge loan costs	0.0	0.4	0.0	2.9
Severance and relocation costs	0.0	1.7	0.5	1.7
Other costs and tax benefit	0.1	(6.5)	0.3	(6.1)
Total accounting charges	$ 0.2	$ 0.9	$ 1.2	$ 5.7

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 25

-Paragraph 23

-URI http://asc.fasb.org/extlink&oid=34752592&loc=d3e1043-128460

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