Debt (details) (5.00% Senior notes due March 15, 2013 [Member], USD $) In Millions, unless otherwise specified	0 Months Ended
Mar. 15, 2013
5.00% Senior notes due March 15, 2013 [Member]
Debt repayment
Debt, principal amount repaid	$ 500
Interest rate (percent)	5.00%

Contractual interest rate for funds borrowed, under the debt agreement.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant