Indebtedness (Senior Notes Narrative) (Details) (Senior notes, net [Member], USD $) In Millions, unless otherwise specified	0 Months Ended
	Jun. 17, 2014	Jun. 17, 2014 3.65% senior notes due July 2024 [Member]	Sep. 30, 2014 4.50% senior notes due September 2014 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 300	$ 400
Debt instrument, interest rate		3.65%	4.50%
Debt instrument, interest rate, effective percentage		3.673%
Percentage of principal that must be repaid in addition to accrued interest and applicable make-whole payments under call feature of notes	100.00%