Stockholders' Equity, Restricted Stock Unit Activity (Details) - Restricted Stock Units [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Number of Shares [Abstract]
Non-vested at beginning of period (in shares)	2,374
Granted (in shares)	1,548
Vested (in shares)	(834)
Cancelled/forfeited (in shares)	(411)
Non-vested at end of period (in shares)	2,677	2,374
Weighted Average Grant Date Fair Value per Share [Abstract]
Non-vested at beginning of period (in dollars per share)	$ 58.81
Granted (in dollars per share)	57.69	$ 60.86	$ 60.23
Vested (in dollars per share)	57.47
Cancelled/forfeited (in dollars per share)	59.24
Non-vested at end of period (in dollars per share)	$ 58.51	$ 58.81
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation cost related to non-vested units	$ 57.0
Weighted average period for recognition	1 year 2 months 12 days