Subsequent Events (Details) (USD $) In Millions, unless otherwise specified		0 Months Ended
	Sep. 30, 2012	Nov. 02, 2012 2.650% Senior Notes due 2019 [Member]
Subsequent Event [Line Items]
Proceeds from Issuance of Senior Long-term Debt		$ 400
Debt Instrument, Interest Rate, Stated Percentage	3.875%	2.65%