Stockholders' Equity (Narrative) (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014 employee_group	Mar. 31, 2013
Components of Stockholders' Equity [Line Items]
Total intrinsic value of options exercised	$ 101,500,000	$ 50,000,000
Proceeds from issuance of common stock	32,448,000	39,146,000
Number of employee groups	2
Weighted-average fair value of employee stock options granted per share	$ 221.79	$ 72.71
Stock-based compensation expense	25,800,000	17,700,000
Income tax benefit	$ 9,900,000	$ 6,800,000
2011 Stock Plan [Member]
Components of Stockholders' Equity [Line Items]
Shares reserved for future issuance	3.3