Equity Compensation (Restricted Stock Units) (Details) - Restricted stock units
6 Months Ended
Jun. 30, 2017
$ / shares
shares
Restricted stock units  
Non-vested balance at beginning of period (in shares) 1,396,387
Awarded 781,010
Vested (500,389)
Forfeited (53,317)
Non-vested balance at end of period (in shares) 1,623,691
Weighted Average Grant Date Fair Value  
Non-vested balance at beginning of period (in dollars per share) | $ / shares $ 7.60
Awarded (in dollars per share) | $ / shares 11.23
Vested (in dollars per share) | $ / shares 7.45
Forfeited (in dollars per share) | $ / shares 8.62
Non-vested balance at end of period (in dollars per share) | $ / shares $ 9.36
Shares withheld for tax purposes (in shares) 170,673
Issuance of shares net of shares withheld (in shares) 329,716