Derivative Financial Instruments (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Summary of Derivative Instruments [Abstract]
Derivative transactions entered into	$ 181	$ 1,443	$ 248	$ 2,047
Derivative transactions terminated	$ 175	$ 1,523	$ 242	$ 2,065