Capital Transactions - Information About Stock Options Outstanding (Details)	12 Months Ended
	Dec. 31, 2017 $ / shares shares
$8.00 to $12.99
Stock options, exercise price
Exercise price range, low end of range (in dollars per share)	$ 8.00
Exercise price range, high end of range (in dollars per share)	$ 12.99
Options Outstanding
Number of options outstanding (in shares) | shares	79,990
Options outstanding, Weighted Average Remaining Contractual Life	3 years 1 month 6 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 12.06
Options Exercisable
Number of options Exercisable (in shares) | shares	79,990
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 12.06
$13.00 to $14.99
Stock options, exercise price
Exercise price range, low end of range (in dollars per share)	13.00
Exercise price range, high end of range (in dollars per share)	$ 14.99
Options Outstanding
Number of options outstanding (in shares) | shares	371,480
Options outstanding, Weighted Average Remaining Contractual Life	4 years 2 months 12 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 14.02
Options Exercisable
Number of options Exercisable (in shares) | shares	173,481
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 13.67
$15.00 to $19.00
Stock options, exercise price
Exercise price range, low end of range (in dollars per share)	15.00
Exercise price range, high end of range (in dollars per share)	$ 19.00
Options Outstanding
Number of options outstanding (in shares) | shares	6,633
Options outstanding, Weighted Average Remaining Contractual Life	4 years 9 months 18 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 17.77
Options Exercisable
Number of options Exercisable (in shares) | shares	721
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 15.03
$8.00 to $19.00
Stock options, exercise price
Exercise price range, low end of range (in dollars per share)	8.00
Exercise price range, high end of range (in dollars per share)	$ 19.00
Options Outstanding
Number of options outstanding (in shares) | shares	458,103
Options outstanding, Weighted Average Remaining Contractual Life	4 years
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 13.73
Options Exercisable
Number of options Exercisable (in shares) | shares	254,192
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 13.17