Stock Options, Restricted Stock, and Dividend Reinvestment Plans - Summary of Stock Option Activity (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares
Options Outstanding
Beginning of period, Outstanding (in shares) | shares	5,904,687
Options granted (in shares) | shares	530,787
Options exercised (in shares) | shares	(895,695)
Options expired/cancelled (in shares) | shares	(607,998)
End of period, Outstanding (in shares) | shares	4,931,781
Options exercisable (in shares) | shares	3,347,210
Options expected to vest (in shares) | shares	1,584,571
Weighted Average Exercise Price (per share)
Beginning of period, weighted average exercise price (in dollars per share) | $ / shares	$ 16.16
Options granted, weighted average exercise price (in dollars per share) | $ / shares	15.43
Options exercised, weighted average exercise price (in dollars per share) | $ / shares	10.79
Options expired/cancelled, weighted average exercise price (in dollars per share) | $ / shares	27.94
End of period, weighted average exercise price (in dollars per share) | $ / shares	$ 15.61
Outstanding, weighted average contractual term	3 years 29 days
Outstanding, aggregate intrinsic value | $	$ 13,385
Options exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 15.76
Options exercisable, weighted average contractual term	2 years 3 months 25 days
Options exercisable, aggregate intrinsic value | $	$ 10,060
Options expected to vest, weighted average exercise price (in dollars per share) | $ / shares	$ 15.28
Options expected to vest, weighted average remaining contractual term	4 years 8 months 4 days
Options expected to vest, aggregate intrinsic value | $	$ 3,325