Convertible Senior Notes (Narrative) (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended			0 Months Ended
	Mar. 31, 2015		Mar. 31, 2014	Apr. 30, 2014	Dec. 31, 2014
Debt Instrument [Line Items]
Amount used to repurchase stock	$ 124,928,000		$ 0
Convertible notes	1,300,872,000				1,292,953,000
Purchase From Accelerated Share Repurchase [Member]
Debt Instrument [Line Items]
Stock repurchased during period, value				1,400,000,000
Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				1,000
Convertible debt				1,440,000,000
Stated interest rate percentage				0.50%
Proceeds from convertible debt				1,420,000,000
Payments for (proceeds from) hedge, investing activities				82,600,000
Stock repurchased during period, value				1,500,000,000
Convertible debt, conversion ratio				0.011111
Convertible debt, conversion price (in dollars per share)	$ 90.00
Repurchase price as a percent of principal amount				100.00%
Amortization of debt discount, effective interest method, percent	3.00%
Equity component	162,869,000	[1]
Deferred tax liability, equity component	8,200,000
Shares Of Common Stock Covered By Note Hedges				16.0
Class of warrant or right, exercise price of warrants or rights (in dollars per share)				120
Privately Negotiated Transaction [Member]
Debt Instrument [Line Items]
Amount used to repurchase stock				101,000,000
Level 2 [Member] | Carrying Value [Member] | Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Convertible notes	$ 1,300,872,000

[1] Recorded in the condensed consolidated balance sheet within additional paid-in capital.