Capital Stock (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	1 Months Ended			3 Months Ended	9 Months Ended
	Jul. 31, 2016	Apr. 30, 2016	Feb. 29, 2016	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015
Class of Stock Disclosures [Abstract]
Cash dividends declared, per share of common stock	$ 0.38	$ 0.38	$ 0.38	$ 1.14
Stock Repurchased During Period, Shares					135
Payments for Repurchase of Common Stock					$ 13	$ 446
2012 $405.0 Million Repurchase Agreement [Member]
Stock Repurchase Program, Remaining Authorized Repurchase Amount				$ 1,870	$ 1,870