Stockholders' Equity - Narrative (Details) (USD $) Share data in Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Oct. 31, 2013
Stockholders' Equity Note [Abstract]
Stock repurchase program, authorized amount					$ 750,000,000
Shares repurchased during period (in shares)			3.9
Value of shares repurchased during period			226,500,000
Amortization expense from capitalized stock-based compensation	$ 3,600,000	$ 2,200,000	$ 7,500,000	$ 6,100,000