Stockholders' Equity - Restricted Stock Units (Details) - Restricted Stock Units (RSUs) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Number of Shares
Unvested at beginning of period (in shares)	[1]			116,409
Granted (in shares)				26,264
Vested (in shares)				(33,820)
Forfeited (in shares)				(4,351)
Unvested at end of period (in shares)	[1]	104,502		104,502
Weighted Average Grant Date Fair Value
Unvested at beginning of period (in dollars per share)				$ 65.95
Granted (in dollars per share)				112.08
Vested (in dollars per share)				58.27
Forfeited (in dollars per share)				73.91
Unvested at end of period (in dollars per share)		$ 79.69		$ 79.69
Fair value of vested RSUs		$ 1,210	$ 894	$ 3,840	$ 2,380

[1] Unvested shares include inducement awards issued in connection with an acquisition in 2014 and are subject to the terms, restrictions, and conditions of separate non-plan RSU award agreements.