Stock Options, Restricted Stock, and Dividend Reinvestment Plans - Summary of Stock Option Activity (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) $ / shares shares
Options Outstanding
Beginning of period, outstanding (in shares) | shares	7,749,082
Options granted (in shares) | shares	155,124
Options exercised (in shares) | shares	(2,302,642)
Options expired/canceled (in shares) | shares	(620,635)
End of period, outstanding (in shares) | shares	4,980,929
Options exercisable (in shares) | shares	3,697,062
Options expected to vest (in shares) | shares	1,283,867
Weighted Average Exercise Price (per share)
Beginning of period, weighted average exercise price (in dollars per share) | $ / shares	$ 15.20
Options granted, weighted average exercise price (in dollars per share) | $ / shares	14.44
Options exercised, weighted average exercise price (in dollars per share) | $ / shares	11.88
Options expired/canceled, weighted average exercise price (in dollars per share) | $ / shares	22.44
End of period, weighted average exercise price (in dollars per share) | $ / shares	15.81
Options exercisable, weighted average exercise price (in dollars per share) | $ / shares	15.95
Options expected to vest, weighted average exercise price (in dollars per share) | $ / shares	$ 15.15
Outstanding, weighted average contractual term	3 years 11 months 26 days
Outstanding, aggregate intrinsic value | $	$ 7
Options exercisable, weighted average contractual term	3 years 6 months 3 days
Options exercisable, aggregate intrinsic value | $	$ 6
Options expected to vest, weighted average remaining contractual term	4 years 4 months 20 days
Options expected to vest, aggregate intrinsic value | $	$ 1