Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.28,29)

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

Name:	us-gaap_TreasuryStockShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

1. Basis of Presentation and Use of Estimates Treasury Shares (Details) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2012 Treasury Class B [Member]	Dec. 31, 2011 Treasury Class B [Member]	Jun. 30, 2011 Treasury Class B [Member]	Jun. 30, 2012 Treasury Class A [Member]	Dec. 31, 2011 Treasury Class A [Member]	Jun. 30, 2011 Treasury Class A [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount	$ 18.0
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 3.3
Treasury Stock, Shares		917	0	0	122	0	0