Convertible Senior Notes (Narrative) (Details) - USD ($)			3 Months Ended	6 Months Ended		12 Months Ended
		Apr. 30, 2014	Jun. 30, 2014	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2014	Dec. 31, 2015
Debt Instrument [Line Items]
Amount used to repurchase stock				$ 28,689,000	$ 172,132,000
Convertible notes				$ 1,329,478,000			$ 1,311,071,000
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]
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				0.0111111
Debt instrument, face amount				$ 1,000
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%
Convertible notes				$ 1,329,478,000			1,311,071,000
Equity component	[1]			162,869,000			$ 162,869,000
Deferred tax liability, equity component				$ 8,200,000
Shares of common stock covered by note hedges (shares)		16,000,000
Warrant transaction (shares)		16,000,000
Initial strike price of warrants (in dollars per share)		$ 120.0
Warrants exercised (shares)				0
Privately Negotiated Transaction [Member]
Debt Instrument [Line Items]
Amount used to repurchase stock			$ 101,000,000

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