Stock-based compensation (Tables)

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement [Abstract]

Summary of Non-vested PSU, Restricted Stock, and RSU Activity

The following table summarizes our non-vested PSU, restricted stock and RSU activity for 2019. 

Non-vested PSU, restricted stock and RSU activity	Number of shares		Weighted-average fair value at grant date
Non-vested PSUs, restricted stock and RSUs at Dec. 31, 2018	14,211,712		$	49.43
Granted	6,179,808		51.59
Vested	(6,201,276	)	43.21
Forfeited	(1,456,946	)	49.74
Non-vested PSUs, restricted stock and RSUs at Dec. 31, 2019	12,733,298		$	50.77

Summary of Stock Option Activity

A summary of the status of our options as of Dec. 31, 2019, and changes during the year, is presented below:

Stock option activity	Shares subject to option		Weighted-average exercise price		Weighted-average remaining contractual term (in years)
Balance at Dec. 31, 2018	6,714,283		$	25.67	2.0
Granted	—		—
Exercised	(2,543,235	)	25.14
Canceled/Expired	(27,473	)	21.93
Balance at Dec. 31, 2019	4,143,575		$	26.03	1.4
Vested and expected to vest at Dec. 31, 2019	4,143,575		26.03		1.4
Exercisable at Dec. 31, 2019	4,143,575		26.03		1.4

Summary of Stock Options Outstanding by Exercise Price

Stock options outstanding at Dec. 31, 2019
	Options outstanding					Options exercisable (a)
Range of exercise prices	Outstanding	Weighted-average remaining contractual life (in years)	Weighted-average exercise price			Exercisable	Weighted-average exercise price
$ 18 to 31	4,143,575	1.4		$	26.03	4,143,575		$	26.03

(a)

At Dec. 31, 2018 and Dec. 31, 2017, 6,714,283 and 9,302,140 options were exercisable at a weighted-average price per common share of $25.67 and $27.27, respectively.

Aggregate Intrinsic Value of Options

Aggregate intrinsic value of options
(in millions)	2019		2018		2017
Outstanding at Dec. 31,	$	101	$	144	$	247
Exercisable at Dec. 31,	$	101	$	144	$	247