Long-Term Debt (Senior Notes) (Narrative) (Details) $ in Billions	9 Months Ended
	Sep. 30, 2015 USD ($) d Rate
Debt Instruments [Abstract]
Unsecured senior notes description	The Company has issued $1.4 billion aggregate principal amount of unsecured senior notes due between January of 2021 and June of 2023 with United Missouri Bank, N.A. as trustee. Interest on the senior notes, ranging from 3.800% to 4.875%, is payable biannually and is computed on the basis of a 360-day year.
Aggregate principle of unsecured senior notes | $	$ 1.4
Maturity date range, minimum	Jan. 14, 2021
Maturity date range, maximum	Jun. 20, 2023
Interest rate of notes, minimum	3.80%
Interest rate of notes, maximum	4.875%
Number of days in annual interest calculation period | d	360
Debt instrument covenant description	Each of the senior notes is subject to certain customary covenants, with which the Company complied as of September 30, 2015.