Equity Incentive Plans - Changes in performance stock awards (Details) - Performance stock awards - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock units activity
Outstanding at the beginning of the period (in shares)	951
Granted (in shares)	442
Adjustment for performance achievement (in shares)	338
Vested (in shares)	(676)
Forfeited (in shares)	(81)
Outstanding at the end of the period (in shares)	974	951
Weighted average grant date fair value
Weighted average grant date fair value, nonvested at the beginning of the period (in dollars per share)	$ 100.89
Weighted average grant date fair value, granted (in dollars per share)	107.14	$ 123,480,000	$ 92,490,000
Weighted average grant date fair value, adjustment for performance achievement (in dollars per share)	92.88
Weighted average grant date fair value, vested (in dollars per share)	92.88
Weighted average grant date fair value, forfeited (in dollars per share)	107.91
Weighted average grant date fair value, nonvested at the end of the period (in dollars per share)	$ 105.92	$ 100.89
Risk-free rate, high end of the range (as a percent)	0.20%
Expected volatility rate (as a percent)	29.90%
Weighted average volatility (as a percent)	37.40%
Weighted average expected term	2 years 10 months 24 days
Total fair value of restricted stock and restricted stock units vested	$ 70	$ 101	$ 65