Capital Stock (Textuals) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Aug. 24, 2015	Aug. 20, 2013	Aug. 18, 2012
Equity, Class of Treasury Stock [Line Items]
Shares repurchased (in shares - less than 0.1 million)	100,000	100,000	100,000	100,000
Shares repurchased (less than $1 million)	$ 1,000,000	$ 1,000,000	$ 3,000,000
2015 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount					$ 500,000,000
Remaining authorized amount of repurchase	$ 420,000,000		$ 420,000,000
2013 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount						$ 250,000,000
Shares repurchased (in shares - less than 0.1 million)	600,000			2,000,000.0
Shares repurchased (less than $1 million)	$ 20,000,000			$ 70,000,000
2012 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount							$ 2,000,000.0
Shares repurchased (in shares - less than 0.1 million)	0	800,000.0	0	800,000
Shares repurchased (less than $1 million)	$ 0	$ 25,000,000	$ 0	$ 25,000,000
Remaining authorized number of shares to be repurchased (in shares)	300,000		300,000
Remaining authorized amount of repurchase	$ 13,000,000		$ 13,000,000