Common Stock and Stock Compensation - Stock Option Activity (Details)	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares Subject to Option, Outstanding, Beginning Balance | shares	39,929,319
Shares Subject to Option, Exercised | shares	4,032,729
Shares Subject to Options, Cancelled | shares	146,684
Shares Subject to Option, Outstanding, Ending Balance | shares	35,749,906
Shares Subject to Options, Exercisable, Ending Balance | shares	25,857,590
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Options Outstanding, Weighted Average Exercise Price, Beginning of Period (in dollars per share) | $ / shares	$ 40.55
Options Exercised, Weighted Average Exercise Price (in dollars per share) | $ / shares	36.84
Options Cancelled, Weighted Average Exercise Price (in dollars per share) | $ / shares	42.31
Options Outstanding, Weighted Average Exercise Price, End of Period (in dollars per share) | $ / shares	40.96
Options Exercisable, Weighted Average Exercise Price, End of Period (in dollars per share) | $ / shares	$ 40.53