Stock-based Compensation - Effect on Shares Outstanding and Treasury Shares (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Changes in Treasury Stock [Line Items]
Treasury stock (in shares)	729,547,527	694,189,127	658,012,970	632,636,970
Repurchases	51,384,339	61,665,209	77,564,013
Total issued (in shares)	(16,018,408)	(25,481,874)	(52,175,104)
Director
Schedule of Changes in Treasury Stock [Line Items]
Director deferred stock issued (in shares)	(7,531)	(7,178)	(12,909)
Employee Stock Option
Schedule of Changes in Treasury Stock [Line Items]
Exercised (in shares)	(11,953,455)	(19,503,382)	(45,507,711)
Stock applied to taxes			0
Total issued (in shares)	(13,477,157)	(21,280,948)	(47,894,545)
Stock applied to exercises or taxes	8,562	6,618
Employee Stock Option | Director
Schedule of Changes in Treasury Stock [Line Items]
Director deferred stock issued (in shares)	0	0	0
Restricted Stock Units (RSUs)
Schedule of Changes in Treasury Stock [Line Items]
Vested RSUs (in shares)	(3,386,415)	(5,609,627)	(5,741,981)
Stock applied to taxes			1,461,422
Total issued (in shares)	(2,541,251)	(4,200,926)	(4,280,559)
Stock applied to exercises or taxes	845,164	1,408,701
Restricted Stock Units (RSUs) | Director
Schedule of Changes in Treasury Stock [Line Items]
Director deferred stock issued (in shares)	0	0	0
Employee stock purchase plan
Schedule of Changes in Treasury Stock [Line Items]
Exercised (in shares)	(1,532,264)
Employee stock purchase plan | Employee Stock Option
Schedule of Changes in Treasury Stock [Line Items]
Exercised (in shares)	(1,532,264)	(1,784,184)	(2,386,834)
Employee stock purchase plan | Restricted Stock Units (RSUs)
Schedule of Changes in Treasury Stock [Line Items]
Vested RSUs (in shares)	0	0	0