Convertible Senior Notes (Note Hedges) (Details) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2013
Debt Disclosure [Abstract]
Aggregate amount of hedge	$ 58.2
Shares exercisable upon conversion	9,800,000
Fair value of Note Hedge	$ 149.6

Net fair value of all derivative instruments designated as fair value hedging instruments.

Reference 1: 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

Name:	us-gaap_FairValueHedgesAtFairValueNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant