Equity and Share Based Payments - Stock Options (Details) - Stock options $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2018 USD ($) $ / shares shares
Number of Shares
Options outstanding at beginning of period (in shares) | shares	1,582,754
Options granted (in shares) | shares	90,000
Options exercised (in shares) | shares	(97,910)
Options forfeited / cancelled (in shares) | shares	(370,431)
Options outstanding at end of year (in shares) | shares	1,204,413
Options exercisable at end of year (in shares) | shares	939,915
Weighted-Average Exercise Price
Options outstanding at beginning of period (in dollars per share) | $ / shares	$ 13.61
Options granted (in dollars per share) | $ / shares	9.52
Options exercised (in dollars per share) | $ / shares	4.44
Options forfeited / cancelled (in dollars per share) | $ / shares	15.84
Options outstanding at end of year (in dollars per share) | $ / shares	13.68
Options exercisable at end of year (in dollars per share) | $ / shares	$ 13.62
Additional disclosure related to options
Unrecognized compensation cost | $	$ 1.2
Weighted-average period over which compensation cost is expected to be recognized	1 year 10 months 24 days