Capital Stock (Stock Repurchases Pursuant To Board Of Director Authorizations) (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity, Class of Treasury Stock [Line Items]
Stock repurchased during period, shares	27.8	9.0	7.7
Stock repurchase program remaining authorization	9.0
1997 Authorization [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchased during period, shares	0.9	3.2	0.0
Stock repurchase program remaining authorization	0.0
2007 Authorization [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchased during period, shares	0.9	5.8	7.7
Stock repurchase program remaining authorization	0.0
2014 Authorization [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchased during period, shares	20.0	0.0	0.0
Stock repurchase program remaining authorization	0.0
2015 Authorization [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchased during period, shares	6.0	0.0	0.0
Stock repurchase program remaining authorization	9.0