Convertible Senior Notes - Additional Information (Details) - USD ($) $ / shares in Units, shares in Millions			3 Months Ended		12 Months Ended
		Apr. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2015
Debt Instrument [Line Items]
Proceeds from convertible debt offering					$ 0	$ 1,415,717,000	$ 0
Stock repurchase program, authorized amount				$ 1,500,000,000.0	6,300,000,000			$ 500,000,000
Payments for Repurchase of Common Stock					755,704,000	1,640,885,000	$ 406,326,000
Convertible Senior Notes					$ 1,324,992,000	$ 1,292,953,000
Senior Notes Due 2019
Debt Instrument [Line Items]
Shares Of Common Stock Covered By Note Hedges		16.0
Debt Instrument, Convertible, Conversion Ratio		0.011111
Convertible Debt		$ 1,440,000,000.00
Debt Instrument, Interest Rate, Stated Percentage		0.50%
Proceeds from convertible debt offering		$ 1,420,000,000
Payments for (Proceeds from) Hedge, Investing Activities		82,600,000
Convertible debt, conversion price (in dollars per share)					$ 90.00
Debt Instrument, Face Amount		$ 1,000
Repurchase Price as a Percent of Principal Amount		100.00%
Amortization, Effective Interest Method, Percent					3.00%
Convertible Senior Notes					$ 1,324,992,000
Equity component	[1]				162,869,000
Deferred Tax Liabilities, Deferred Expense, Deferred Financing Costs					$ 8,200,000
Additional Warrant Transaction		16.0
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 120.0
Privately Negotiated Transaction [Member]
Debt Instrument [Line Items]
Payments for Repurchase of Common Stock				101,000,000
Purchase From Accelerated Share Repurchase [Member]
Debt Instrument [Line Items]
Shares repurchased under the ASR			$ 1,400,000,000	$ 1,400,000,000

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