Long-term Incentive Plan (Schedule of stock options outstanding activity) (Details)
12 Months Ended
Dec. 31, 2016
$ / shares
shares
Stock option activity rollforward  
Number of Options, Outstanding, Beginning Balance | shares 259,311
Number of Options Exercised | shares (85,926)
Number of Options Canceled | shares (58,406)
Number of Options, Outstanding, Ending Balance | shares 114,979
Weighted average price per share  
Weighted Average Exercise Price, Outstanding Beginning Balance | $ / shares $ 8.37
Weighted Average Exercise Price, Exercised | $ / shares 1.81
Weighted Average Exercise Price, Canceled | $ / shares 18.33
Weighted Average Exercise Price, Outstanding Ending Balance | $ / shares $ 8.21