Guarantor Condensed Consolidating Financial Statements (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011
Senior Notes, 5.625% Due 2012 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate, stated percentage	5.625%
Senior notes	$ 300.0
Debt instrument, maturity date	Apr. 17, 2012
Senior Notes, 5.375% Due 2013 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate, stated percentage	5.375%
Senior notes	350.0
Debt instrument, maturity date	Feb. 27, 2013
Senior Notes, 5.375% Due 2014 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate, stated percentage	5.375%
Senior notes	$ 200.0
Debt instrument, maturity date	Dec. 15, 2014

Date when the debt instrument is scheduled to be fully repaid, which may be presented in a variety of ways (year, month and year, day, month and year, quarter, etc.).

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 3: 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)(2))

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

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration