Notes Payable (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	6 Months Ended		12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2011	Nov. 06, 2013
Convertible Notes Payable [Abstract]
Contractual interest rate - Notes						0.00%
Notes Maturity Date			Nov. 01, 2018
Notes, par value			$ 575,000,000
Converted number of shares			7.8
Conversion rate			13.54
Notes face amount			1,000
Initial conversion price, per share						$ 73.88
Terms of conversion feature			July 1, 2018
Earliest date of conversion			Mar. 31, 2014
Number of days out of 30 that common stock price exceeded conversion price, days			20
Number of consecutive trading days in a period			30 days
Threshold percentage of stock price trigger			100.00%
Percentage of purchase price of Notes which should be paid upon fundamental change			100.00%
Deferred tax liability			6,600,000
Price per share (usd per share)			$ 56.01
Remaining life of the Notes			58 months
Note Hedged shares of common stock covered			7.8
Purchase of convertible note hedge	0	0	135,815,000	0	0
Issuance of warrants (in shares)			7.8
Exercise price of warrants issued (usd per share)						107.46
Proceeds from issuance of warrants	$ 0	$ 0	$ 84,525,000	$ 0	$ 0