Stockholders' Equity - Summary of Anti-Dilutive Options Excluded (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Stockholders' Equity Note [Abstract]
Options to purchase shares of common stock	2,169,565	1,313,261	1,823,031	1,263,599
Weighted average exercise prices of options	$ 54.83	$ 54.00	$ 54.60	$ 54.00