Equity (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended			0 Months Ended		3 Months Ended	4 Months Ended
	Jun. 30, 2014	Jun. 30, 2014 2013 Repurchase Program	Dec. 04, 2013 2013 Repurchase Program	Apr. 02, 2013 Accelerated Share Repurchase Program	Mar. 25, 2013 Accelerated Share Repurchase Program	Jun. 30, 2013 Accelerated Share Repurchase Program	Jul. 25, 2013 Accelerated Share Repurchase Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program number of shares authorized to be repurchased (in shares)			50,000,000
Maximum number of shares authorized for repurchase under stock repurchase plan as percentage of outstanding common stock			18.00%
Remaining shares available under repurchase program (in shares)		45,600,000
Repurchase of additional shares (in shares)					$ 500
Shares received on initial delivery (in shares)						7,200,000
Additional shares received (in shares)				1,400,000			700,000
Accelerated share repurchases, final price paid (in dollars per share)							$ 53.7995
Accelerated share repurchases, cumulative shares repurchased (in shares)							9,300,000
Interest in joint venture minimum percentage	20.00%
Agreement terms, change of control, put option for minority interest ownership, effective period	15 days