Convertible Senior Notes (Narrative) (Details) - USD ($)		3 Months Ended	9 Months Ended		12 Months Ended
	Apr. 30, 2014	Jun. 30, 2014	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2015
Debt Instrument [Line Items]
Amount used to repurchase stock			$ 28,689,000	$ 398,070,000
Convertible notes			1,338,782,000			$ 0
Temporary equity			87,841,000			0
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			$ 1,338,782,000		$ 1,440,000,000	1,311,071,000
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			$ 1,340,000,000
Deferred tax liability, equity component			8,200,000
Temporary equity			$ 87,841,000			$ 0
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