Debt, Extinguishment (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Extinguishment of Debt [Line Items]
Stated Interest Rate Percentage - Debt Instruments	3.75%
Maturity Date - Debt Instrument	Jan. 15, 2034
First Conversion Date	Jan. 15, 2009
Number of Notes Converted	3,522
Cash Payments for Debt Conversions (in millions)	$ 5.6
Deferred Tax Liability (in millions)	0.3
Per Note Conversion Price	$ 466
Excess above Principal Note Amount (in millions)	$ 23
3.75% Senior Subordinated Convertible Notes, Due 2034
Extinguishment of Debt [Line Items]
If converted, issuance of common stock shares	188,732