Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2018

Equity [Abstract]

Schedule of share repurchases and authorizations

The following table summarizes the Company’s share repurchase authorizations of its Class A common stock through September 30, 2018, as well as historical purchases:

Board authorization dates	December 2017		December 2016		December 2015
Date program became effective	March 2018		April 2017		February 2016		Total
	(in millions, except average price data)
Board authorization	$	4,000	$	4,000	$	4,000	$	12,000
Dollar value of shares repurchased during the nine months ended September 30, 2017	$	—	$	1,735	$	996	$	2,731
Remaining authorization at December 31, 2017	$	4,000	$	1,234	$	—	$	5,234
Dollar value of shares repurchased during the nine months ended September 30, 2018	$	2,811	$	1,234	$	—	$	4,045
Remaining authorization at September 30, 2018	$	1,189	$	—	$	—	$	1,189
Shares repurchased during the nine months ended September 30, 2017	—		14.0		9.1		23.1
Average price paid per share during the nine months ended September 30, 2017	$	—	$	123.81	$	109.16	$	118.03
Shares repurchased during the nine months ended September 30, 2018	14.6		7.2		—		21.8
Average price paid per share during the nine months ended September 30, 2018	$	192.82	$	171.11	$	—	$	185.64
Cumulative shares repurchased through September 30, 2018	14.6		28.2		40.4		83.2
Cumulative average price paid per share	$	192.82	$	141.99	$	99.10	$	130.07

Schedule of Changes in Common Stock Outstanding

The following table presents the changes in the Company’s outstanding Class A and Class B common stock for the nine months ended September 30, 2018:

	Outstanding Shares
	Class A		Class B
	(in millions)
Balance at December 31, 2017	1,039.7		14.1
Purchases of treasury stock	(21.8	)	—
Share-based payments	2.6		—
Conversion of Class B to Class A common stock	2.2		(2.2	)
Balance at September 30, 2018	1,022.7		11.9