Shareholders' Equity (Details) (USD $)	1 Months Ended	3 Months Ended		12 Months Ended
	Oct. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2012
Stockholders' Equity Note [Abstract]
Treasury Stock, Value, Acquired, Cost Method		$ 55,000,000	$ 1,100,000,000
Stock Repurchase Program, Authorized Amount	$ 5,000,000,000			$ 1,500,000,000