Stockholders' Equity (Share Repurchase Program) (Narrative) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		1 Months Ended		3 Months Ended	1 Months Ended			6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Feb. 28, 2014 January 2014 Buyback Plan [Member]	Jan. 31, 2014 January 2014 Buyback Plan [Member]	Mar. 31, 2014 January 2014 Buyback Plan [Member]	Feb. 28, 2014 Q1 2014 Open Market Purchases [Member]	Feb. 28, 2013 December 2012 Buyback Plan [Member]	Dec. 31, 2012 December 2012 Buyback Plan [Member]	Jun. 30, 2013 December 2012 Buyback Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Share buyback plan, Authorized Amount				$ 5,000				$ 1,000
Prepayment for the repurchase of common stock	1,061	1,000	1,000				1,000
Payment for the repurchase of common stock						$ 61
Stock Repurchased and Retired During Period, Shares					12.5	1.0			20.4
Treasury Stock Acquired, Average Cost Per Share						$ 61.32
Percentage of share repurchase agreement completed					80.00%