Long-Term Debt (Senior Notes) (Details) (USD $) In Billions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014 D Rate
Aggregate principle of unsecured senior notes	$ 1.4
Interest rate of notes, minimum	3.80%
Interest rate of notes, maximum	4.875%
Number of days in annual interest calculation period	360
Debt instrument covenant description	Each of the senior notes is subject to certain customary covenants, with which the Company complied as of June 30, 2014.