Benefit Plans - Option Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Additional disclosure
Intrinsic value	$ 4,200	$ 8,400	$ 7,700
Compensation expense	$ 132	$ 571	$ 927
Stock option
Number of Stock Options Outstanding
Options outstanding at the beginning of the year (in shares)	681,933
Granted (in shares)	0
Exercised (in shares)	(220,118)
Forfeited and expired (in shares)	(8,711)
Options outstanding at the end of the year (in shares)	453,104	681,933
Vested at the end of the year (in shares)	451,424
Weighted Average Exercise Price Per Share
Options outstanding at the beginning of the year (in dollars per share)	$ 15.26
Granted (in dollars per share)	0
Exercised (in dollars per share)	13.17
Forfeited and expired (in dollars per share)	15.84
Options outstanding at the end of the year (in dollars per share)	16.26	$ 15.26
Vested at the end of the year (in dollars per shares)	$ 16.24
Weighted average remaining contractual life
Outstanding at the end of the year	4 years 7 months 28 days
Vested at the end of the year	4 years 7 months 28 days
Additional disclosure
Aggregate intrinsic value, outstanding	$ 7,401
Aggregate Intrinsic value, vested and expected to vest	7,382
Unrecognized compensation expense	$ 8