Net Income Per Share (Narrative) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	1 Months Ended	6 Months Ended
Apr. 30, 2008	Jun. 30, 2011	Apr. 09, 2008
Convertible Notes, convertible amount per share		$ 29.20
Purchase of common stock, shares		13
1.75% Convertible Senior Subordinated Notes Due April 15, 2015 [Member]
Notes, interest rate	1.75%	1.75%
Convertible Notes, maturity date	Apr. 15, 2015	Apr. 15, 2015
Convertible Notes, convertible amount per share		$ 29.20	$ 24.85

The number of shares issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or payments in the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 32
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586

Name:	us-gaap_DebtConversionConvertedInstrumentSharesIssued1
Namespace Prefix:	us-gaap
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration