Fair value of the gross liabilities less the gross assets of a derivative liability or group of derivative liabilities.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13495-108611

Name:	us-gaap_DerivativeLiabilityFairValueNet1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Fair Value Measurements (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Fair Value Measurements Of Financial Instruments [Line Items]
Fair value of Level one assets	$ 615.5	$ 288.3
Foreign Exchange Forward Contract [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Derivative liabilities	0.3
Unobservable Inputs (Level 3) [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Fair value of Level one assets
Equities [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Unrealized gain (loss) on investment securities	$ 17.5