Equity Compensation (Restricted Stock Units) (Details) - Restricted stock units
9 Months Ended
Sep. 30, 2017
$ / shares
shares
Restricted stock units  
Non-vested balance at beginning of period (in shares) 1,396,387
Awarded 782,310
Vested (746,819)
Forfeited (57,917)
Non-vested balance at end of period (in shares) 1,373,961
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 11.26
Vested (in dollars per share) | $ / shares 7.65
Forfeited (in dollars per share) | $ / shares 8.66
Non-vested balance at end of period (in dollars per share) | $ / shares $ 9.61
Shares withheld for tax purposes (in shares) 255,838
Issuance of shares net of shares withheld (in shares) 490,981