Stock Compensation - Effect on Shares Outstanding and Treasury Shares (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Changes in Treasury Stock [Line Items]
Treasury stock (in shares)	757,657,217	744,831,978	729,547,527	694,189,127
Repurchases	30,570,129	35,480,036	51,384,339
Total issued (in shares)	(17,740,140)	(20,181,998)	(16,018,408)
Director
Schedule of Changes in Treasury Stock [Line Items]
Director deferred stock units issued (in shares)	(4,750)	(13,587)	(7,531)
Employee Stock Option
Schedule of Changes in Treasury Stock [Line Items]
Exercised (in shares)	(13,313,019)	(14,516,606)	(11,953,455)
Stock applied to exercises or taxes	0	0	8,562
Total issued (in shares)	(14,378,776)	(15,878,808)	(13,477,157)
Employee Stock Option | Director
Schedule of Changes in Treasury Stock [Line Items]
Director deferred stock units issued (in shares)	0	0	0
Restricted Stock Units (RSUs)
Schedule of Changes in Treasury Stock [Line Items]
Vested RSUs (in shares)	(4,419,464)	(5,639,666)	(3,386,415)
Stock applied to exercises or taxes	1,058,100	1,336,476	845,164
Total issued (in shares)	(3,361,364)	(4,303,190)	(2,541,251)
Restricted Stock Units (RSUs) | Director
Schedule of Changes in Treasury Stock [Line Items]
Director deferred stock units issued (in shares)	0	0	0
Employee stock purchase plan
Schedule of Changes in Treasury Stock [Line Items]
Exercised (in shares)	(1,065,757)
Employee stock purchase plan | Employee Stock Option
Schedule of Changes in Treasury Stock [Line Items]
Exercised (in shares)	(1,065,757)	(1,362,202)	(1,532,264)
Employee stock purchase plan | Restricted Stock Units (RSUs)
Schedule of Changes in Treasury Stock [Line Items]
Vested RSUs (in shares)	0	0	0