Stock Compensation Plans - Summary of Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Options
Outstanding as of beginning of period (in shares)	62,000
Granted (in shares)	0	0
Exercised (in shares)	(53,586)
Forfeited (in shares)	(8,414)
Outstanding as of end of period (in shares)	0	62,000
Exercisable (in shares)	0
Weighted-Average Exercise Price
Outstanding as of beginning of period (in dollars per share)	$ 25.71
Granted (in dollars per share)	0.00
Exercised (in dollars per share)	25.67
Forfeited (in dollars per share)	26.00
Outstanding as of end of period (in dollars per share)	0.00	$ 25.71
Exercisable (in dollars per share)	$ 0.00
Aggregate Intrinsic Value
Outstanding as of beginning of period	$ 219
Exercised	180
Outstanding as of end of period	0	$ 219
Exercisable as of end of period	$ 0
Weighted-Average Remaining Term (in years)
Outstanding		7 months 6 days