Shareholders' Equity (Details) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013
Shareholders' Equity [Abstract]
Number of shares authorized to be repurchased	4.0
Shares issued during the period	6.7

The increase (decrease) during the period in the number of shares issued.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Name:	us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration