Stockholders' Equity (Summary of Common and Treasury Stock) (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Changes in common stock issued and treasury stock
Balance at the beginning of the period (in shares)	924,800,000
Exercise of stock options and conversion of restricted stock units (in shares)	11,500,000
Balance at the end of the period (in shares)	940,100,000.0	924,800,000
Common Stock
Changes in common stock issued and treasury stock
Balance at the beginning of the period (in shares)	924,800,000	906,500,000	880,900,000
Exercise of stock options and conversion of restricted stock units (in shares)	15,300,000	18,300,000	25,000,000
Issuance of common stock for employee benefit plans (in shares)	0	0	600,000
Shares repurchased under share repurchase program (in shares)	0	0	0
Balance at the end of the period (in shares)	940,100,000	924,800,000	906,500,000
Treasury Stock
Changes in common stock issued and treasury stock
Balance at the beginning of the period (in shares)	(124,600,000)	(101,500,000)	(78,700,000)
Exercise of stock options and conversion of restricted stock units (in shares)	(1,200,000)	(1,300,000)	(500,000)
Issuance of common stock for employee benefit plans (in shares)	400,000	200,000	0
Shares repurchased under share repurchase program (in shares)	(28,100,000)	(22,000,000)	(22,300,000)
Balance at the end of the period (in shares)	(153,500,000)	(124,600,000)	(101,500,000)