Stockholders' Equity - Narrative (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 employee_group	Sep. 30, 2013
Components of Stockholders' Equity [Line Items]
Total intrinsic value of options exercised	$ 60,300,000	$ 64,500,000	$ 208,000,000	$ 182,800,000
Proceeds from issuance of common stock	9,877,000	25,561,000	56,794,000	93,553,000
Number of employee groups			2
Weighted-average fair value of employee stock options granted per share	$ 236.96	$ 136.78	$ 217.23	$ 100.08
Stock-based compensation expense	29,900,000	18,500,000	85,000,000	54,200,000
Income tax benefit	$ 11,400,000	$ 7,100,000	$ 32,500,000	$ 20,800,000
2011 Stock Plan [Member]
Components of Stockholders' Equity [Line Items]
Shares reserved for future issuance	3.0		3.0