Share Repurchase Program (Details Textual) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended			1 Months Ended			1 Months Ended			12 Months Ended						12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Jan. 31, 2010 Share Repurchase Program July 2009 [Member]	Jan. 19, 2010 Share Repurchase Program July 2009 [Member]	Jul. 27, 2009 Share Repurchase Program July 2009 [Member]	May 31, 2010 Share Repurchase Program Feb 2010 [Member]	May 26, 2010 Share Repurchase Program Feb 2010 [Member]	Feb. 25, 2010 Share Repurchase Program Feb 2010 [Member]	Dec. 31, 2011 Share Repurchase Program Aug 2010 [Member]	May 31, 2011 Share Repurchase Program Aug 2010 [Member]	May 19, 2011 Share Repurchase Program Aug 2010 [Member]	Aug. 20, 2010 Share Repurchase Program Aug 2010 [Member]	Dec. 31, 2011 Share Repurchase Program Aug 2011 [Member]	Aug. 31, 2011 Share Repurchase Program Aug 2011 [Member]	Dec. 31, 2011 Share Repurchase Program Combination One [Member]
Share Repurchase Program (Textual) [Abstract]
Authorized amount for repurchase of outstanding common stock	$ 3,800					$ 750			$ 250		$ 1,400	$ 1,400	$ 1,000	$ 1,400	$ 750
Authorized amount for additional repurchase of outstanding common stock	750										400
Repurchase of common stock, shares	43.0	27.0			1.1			3.3		15.0						15.6
Average per share price of repurchase of common stock				$ 78.36			$ 76.29			$ 93.05						$ 101.94
Payments for Repurchase of Common Stock	1,586	716	910	90						1,400						1,600
Maximum value of shares repurchased under share re-purchase program														$ 187